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Gemstone Supply Chain

October 24th, 2018 by James L. Sweaney, CGA, FGA. GG

Tanzanite and Tsavorite

National Jeweler, a weekly trade publication, posted an article August 29 about “Gem Legacy”, a nonprofit trust set up by jewelry professionals to support education and vocational training in the local economies of East Africa. The countries of this region are major sources of colored gemstones and diamonds, yet many of those persons who mine these natural treasures live in poverty.

Roger Dery, his wife Ginger and daughter Rachel, of Roger Dery Gem Design, have established Gem Legacy to help the people in these communities develop the skills needed for a better life. Various programs include primary schools, gemological education and gem faceting training. Jobs that used to go to cutting centers in Europe and Asia are now becoming available to the people of Kenya, Tanzania and Mozambique.

It’s a reminder that the beautiful Tanzanites, Tsavorites and Sapphires we love so much don’t just appear like magic. They come to us thru a complicated supply chain that involves the skills and efforts of many human beings. Their traditional value, based on their beauty, durability, and rarity, is also enhanced by the jobs they create.

There are many steps involved in the supply chain that brings gems from the mine to the final consumers. Each step means a job for someone. Here is what we might see with the Tanzanites and Tsavorites of East Africa.

  1. Miners tunnel into gem bearing ore. Methods range from pick and shovel to explosives and jack hammers.
  2. Sorters clean gem ore to find and prepare gem crystals for first sale.
  3. Rough buyers and miners sell sorted rough crystals to cutters.
  4. Cutters re-sort rough, then shape, cut and polish gems.
  5. Graders examine and sort finished gems.
  6. Gem dealers sell finished gems to large supplier firms as well as individual buyers.
  7. Suppliers sell to manufacturing jewelers, retail jewelers, and individuals.
  8. Manufacturing jewelers make the jewelry- big firms have specialists for each step in making jewelry.
    1. Casters or Fabricators
    2. Stone setters
    3. Finishers and polishers
  9. Retail jewelers sell the jewelry to consumers.

As members of the American Gem Society (AGS) and the American Gem Trade Association (AGTA), Mardon Jewelers is committed to transparency about the gems and materials we use in our jewelry. We support efforts like Gem Legacy to improve the lives of the people in the countries of origin. The trust accepts contributions from concerned individuals and organizations. If you’re interested in learning more about the Derys’ nonprofit or would like to donate, visit

Reader’s Choice 2018

September 1st, 2018 by James L. Sweaney, CGA, FGA. GG

Results are in for the 2018 Reader’s Choice Survey by the Riverside Press Enterprise. Thank you, our loyal fans and supporters — You’ve done it again! Mardon Jewelers has been voted the Best Jeweler of the Inland Empire for the Tenth Year in a Row!

This last year has been a time of growth and change at Mardon. We just celebrated our second year in the new shop at Canyon Crest Towne Centre. Our customers love the new location with it’s easy access and parking (enter from Central Ave), and beautiful spacious shopping environment. If you haven’t been to the new Mardon, please come by– you’ll find the same friendly and informative faces, comfortable no pressure atmosphere, and our unique blend of one of a kind and custom jewelry, estate jewelry, and of course, the famous Raincross Collection.

In May 2017, Stephanie Holcomb became a member of our Mardon team. She’s a local gal with lots of personality and great people skills. Stephanie is working with Jenny to manage our social media outreach, and she’s an avid student of gems and jewelry. Please stop by and say hello– Stephanie has a great eye for style and always seems to find just the right piece for her customers.

Diamonds are in the news. Recent scientific discoveries are giving us new insight into the origin of diamonds. One study indicates that the ultra rare natural color blue diamonds containing boron are found in oceanic rocks that have been carried by tectonic movement 400 miles deep into the heart of the earth. Most natural diamonds form at half that depth. In light of this research, Gems and Gemology, the scientific journal of GIA, published a major article, Summer 2018, explaining the causes of color in blue diamonds.

Advances in technology have it feasible to produce laboratory-grown diamonds that are large enough to be faceted. Laboratory-grown diamonds do have a lot to offer the consumer. Their physical characteristics are the same as natural diamonds, so they can be just as sparkly and durable. They are not inexpensive – prices are currently about one third to one half the price of natural diamonds. Traditional jewelry stores are carrying them. One of our biggest suppliers, Stuller, has announced that they will produce laboratory-grown diamonds, so you can order these diamonds at Mardon.

The caveat is that buyers should be aware that because this is a very new product, prices are still in flux. Rarity isn’t part of the value equation of laboratory grown diamonds. Since these laboratory-grown diamonds can be produced efficiently, there isn’t a limit on how many can be produced. More production could easily create an oversupply with resulting price drops, so we recommend that buyers educate themselves thoroughly before buying.

Also, consumers should be aware that these diamonds are being marketed as eco-friendly diamonds via the internet under many names and brands. Laboratory-grown diamonds are created in a factory setting using fossil fuels to produce the high levels of electricity needed to synthesize carbon into diamond. The process requires huge amounts of heat and high temperatures for several months. The Jewelers Vigilance Council, a nonprofit consumer advocacy group, has called upon producers of laboratory-grown diamond to substantiate “eco-friendly” claims, but no evidence has been produced.

As always, Mardon strives to bring you the best values in fine jewelry and the most current and accurate information about jewelry and gems. Thanks again for your Reader’s Choice vote as the Best Jeweler in the Inland Empire– We’ll do our best in the coming year to live up to your expectations.

A Tale of Three Jades

August 21st, 2018 by James L. Sweaney, CGA, FGA. GG

Custom Ring by Mardon with fine Jadeite

Jade is unique in the world of gems because there are several different minerals that are correctly called jade. The history of jade begins as far back as the Stone Age. Jade minerals, including nephrite and jadeite, resist breakage but are soft enough to carve, so they were used to make stone tools by several neolithic cultures, both in Europe and Asia. As far back as ~3400 BC, nephrite was mined in China where it was used mainly as ceremonial carvings and utilitarian objects like cups and incense censers.

While the colors of nephrite are muted and soft, the best jadeite from Burma can be rich emerald green with a beautiful jelly like translucence.  The QianLong Emperor of China (1735 – 1796 ) fell so in love with the fabulous green jadeites from Burma that he went to war with the King of Burma. After the Chinese suffered a disastrous defeat, the two rulers settled their differences. Chinese lapidaries were allowed to locate in Mandalay so they could buy, process and trade in jadeite between the two countries.

To this day, many Chinese people prize bright green Burmese jadeite above all other gems, referring to the best qualities as “feicui” i.e kingfisher green, after the bright green feathers of the local bird. This quality of green jadeite, which looks like mint jelly, is referred to as “Imperial” jade and is one of the most expensive gems on the planet.

Fine Art Deco jadeite platinum ring

One of our customers purchased a group of jade jewelry items recently on a trip to mainland China. The stones were represented as jadeite. The color and overall appearance is similar to “Imperial” jadeite and the price seemed like a bargain, so he bought two bracelets and matching earrings. Soon after buying , he noticed one of the stones was missing and one was broken.

The customer wanted us to replace the two stones but something about the jades didn’t seem quite right. Their color was great but the overall appearance didn’t look like the jadeite we’ve seen. We sent the bracelet to Jeff at Mason Kaye in Denver, a well known jade vendor and expert, for testing to see if the material was dyed.

broken jade

The jade report came back as natural color jade but Jeff couldn’t put a value on the stones. Close examination of this broken piece on one of the bracelets gave us the reason. The jades were cut from very dark green material, shaped into cabochons and then hollowed from the back into a very thin dome– 0.3 mm in fact. That’s about as thick as a chicken’s egg shell! The stones were made to appear translucent by setting the stones over a mirror bright surface.

We think these stones may be omphacite jade, a mineral that is a cousin of jadeite. It’s impossible to separate the two using normal gemological tests. Omphacite is generally very dark green to almost black. Like jadeite, the color is derived from impurities of chromium. If this was very dark material to start, the hollowing out technique allows them to appear to be high quality jade. The obvious problem is durability.

In 2012*, the Gem Trade Laboratory of the GIA tested a stone that appeared to be fine quality green jadeite. The stone tested the same as jadeite with standard gemological tests– same refractive index of 1.66, chrome lines and 437 nanometer line in the visible light spectrum of the desk model spectroscope. One of their gemologists noticed the stone had different look and a somewhat different texture. He tested it with their Raman spectroscope to be omphacite . This was unexpected because the mineralogical description of omphacite showed higher optical properties compared to jadeite. Since this discovery, GIA tested numerous pieces previously thought to be jadeite to be omphacite! GIA has now classified omphacite as a type of jade, described as omphacite jade.

We don’t yet know whether fine omphacite jades will equal the value of fine Imperial jadeite jades. We’ve seen some bright green omphacite jades (not hollowed like the above) offered at auction that were similar in appearance to Imperial jadeite. The market will decide, based on availability and how well consumers will accept these type of jade.

Obviously, in light of situations like we described above and with issues of jade-like materials like maw sit sit, dyed jade and jade imitations, buyer beware! We recommend only buying jade from jade experts and gemologists you know and trust. As members of the American Gem Society, our mission is consumer protection through education, full disclosure and fair business practices– we promise you’ll know just what you are buying and that you’ll pay a fair price for your purchase.


Custom Jewelry by Mardon

June 1st, 2018 by James L. Sweaney, CGA, FGA. GG

Color Change Garnet in Custom 14K Yellow Gold Ring

Recent custom pieces by Mardon show off some reasons why people have us make custom jewelry.

We made this snake ring set with a rare gem for a long time client who has a taste for Asian art. We made her a custom diamond ring several years ago that featured Asian style dragons on both sides of a very nice round diamond. This new piece features a serpent wrapped around a rare color change garnet from Africa.

Color change garnets have been mined in Tanzania, Madagascar and Sri Lanka since the 1980’s. Production has been mostly small stones– this 1.20 ct gem is large for the type. They are a variety of Pyrope Garnet. According to one mineralogist, they are mix of 80% Pyrope, 10% Spessartine, and 10% Almandine. Like the alexandrite, they have the rare property of appearing red to pink in incandescent light and blue green in daylight. Our client has become intrigued by some of the rare gems we feature in our shop, and wanted something very unusual. She was delighted with her new ring.

Unusual Opal Doublet in Custom 14K White Gold Ring

This unusual opal ring was made featuring a high quality opal doublet from a yellow gold ring that our client had worn for years. It was a favorite but she wanted it in white gold. The stone had acquired scratches and dings, so we had it repolished before making the new ring. The new ring shows off the unusual shape of the gem and accents the color of the opal with the sparkle of white diamonds

Art Deco-inspired Custom Ring with Sapphires and Diamon

This unique design is based on a vintage Art Deco ring collected by our client who buys and sells vintage jewelry. She loved the design, but wanted something in white gold that would be good for everyday wear. Our CAD wizard, Jenny, worked with her to develop this great looking white gold ring set with diamonds and blue sapphires. Simply stunning!

Tsavorite Garnet & Diamonds in 14K Gold Pendant with Abalone Shell Texture

This intriguing pendant was made for a couple who’ve traveled extensively and had bought the pear shaped Tsavorite garnet on one of their trips. The owner brought us a sketch of his design. The tricky part was that he wanted a textured surface around the stones that is reminiscent of the surface inside an abalone shell.

Pearl Blossoms

May 29th, 2018 by James L. Sweaney, CGA, FGA. GG

Pearl Blossom Necklace and Earrings- Original Design by Kaye Sweaney

We’re proud to introduce “Pearl Blossoms”, the newest pearl fashions by Kaye Sweaney of Mardon. Kaye calls these “Pearl Blossoms” because they remind her of cherry blossoms and other flowers. These unique pieces are each made by hand from “Keshi” pearls from the pearl farms of Asia. Keshi are accidental pearls which spontaneously form as by products of pearl cultivation. Keshi are produced in both saltwater and freshwater pearl farms.

Kaye saw these bright but irregular freshwater keshi pearls and fell in love with their soft luster and shifting colors known as “orient.”  They reminded her of flower petals, so she  went to work to develop a way to make her lovely “Pearl Blossom” jewels. After much trial and error, she was able to create these beautiful blossoms.

Pearl Blossom Enhancer

You’ll find “Pearl Blossoms” only at Mardon Jewelers, the best jewelry store in Riverside. The Limited Edition earrings start at $75, the 5 blossom necklace is $295. If we don’t have exactly what you’d like, Kaye will be happy to make  special blossoms just for you!

Don’t forget that June is Pearl Month– Pearls, Moonstone, and Alexandrite are the birthstones for June.

Pearl Blossoms are now on display at Mardon Jewelers at the Canyon Crest Towne Centre, 5225 Canyon Crest Drive, #14. It’s best to enter the center from the Central Avenue entrance– we’re the first store left of Rite Aid. We’re open Tuesday thru Saturday, 10 to 5:30.

If you’ve enjoyed the blog about Kaye’s beautiful Pearl Blossoms, please give us a vote of confidence in the 2018 Inland Empire Reader’s Choice survey sponsored by the Press Enterprise. It’s easiest to vote on line — just follow this link.

You can take the entire survey for all your choices for best local shopping, restaurants and services. For your ballot to count, vote for at least 25 categories — it’s easy and fun.  And you can vote every day! Voting ends this Sunday,  June 3.

We thank you for your vote and support– this recognition inspires us and helps us keep going to bring you fine original pieces like Kaye’s Pearl Blossoms found only at Mardon Jewelers.

Antique Victorian Cameo Set

May 18th, 2018 by James L. Sweaney, CGA, FGA. GG

Agate Cameo Necklace and Earrings, circa 1870

This just in– an exciting antique necklace and matching earrings with Agate Cameos, from the Victorian era. Hardstone cameos were associated with mourning jewelry starting as early as the 16th century. Sets like this came into vogue during the reign of Queen Victoria after the death of her beloved husband Prince Albert in 1861. The tassel places this set squarely in the Mid Victorian period, circa 1870-1880

The set consists of a necklace with a centerpiece of fabricated 1oK rose gold, set with a banded agate cameo and freshwater pearls. The center setting is basically a box fabricated by hand from sheet gold. The front is lavishly decorated with hand engraving and taille de epergne enameling. Taille de epergne is a variation of champleve enameling where opaque enamels– usually black– are fired into engraved lines forming a design. This necklace is especially nice compared to others we have seen because of unusual shape, the added leaves and natural pearls, and of course, the tassel. Overall condition is very good, considering the set is ~150 years old!

Left and right facing earrings

The earrings feature matching agate cameos, beautifully made with hand engraving and taille de epergne engraving. One cameo facing left, the other faced right so they both face forward when worn. The earrings are nicely articulated- the middle section is hinged the top where the earwires attach and the little engraved “skirts” below the cameo are also jointed.

Anticlastic handmade chain

The interesting 17 inch chain is completely handmade of 5 mm anticlastic (having opposite curvatures at a given point) wire rings, assembled into units and soldered.

Cameos and intaglios were very popular in the 1800’s. Cameos have the carved figure raised above a level surface, usually of a contrasting color, while intaglios are carved down into the surface, opposite that of a cameo. Kind of like navels– inny or outy!

Shell cameo from the 1920’s

Moonstone intaglio from the 19th Century

Hardstone cameos are most often carved from banded agate so that the carved figure is a light color that contrasts with the dark base layer. This set is black and white, others can be brown and white or orangy pink and white. Hardstone cameos are more expensive than cameos carved from shell because the carving is  difficult and time consuming. As such, hardstone cameos are more rare than shell cameos and are very collectible.

Sold as a set only, I-27903, this wonderful antique necklace with matching earrings is now showing in our estate department, Tuesday thru Saturday, 10 -5:30.

If you enjoyed this blog, please give us a vote for Best Jeweler in the 2018 Reader’s Choice survey– it’s easy! You can use a mail-in ballot from the daily newspaper of the Riverside Press Enterprise or even even better, vote online at

And, you can vote once every day! We hope you’ll help us make it 10 years in a row as Best Jeweler in the Inland Empire. Thanks for your support and your vote!

Beer Walk, Canyon Crest

May 1st, 2018 by James L. Sweaney, CGA, FGA. GG

Craft Beer Walk Poster

The 4th Annual Craft Beer Walk at Canyon Crest is next Saturday, May 5.

Press Enterprise Reader’s Choice

April 27th, 2018 by James L. Sweaney, CGA, FGA. GG

The Press has announced that voting for the annual Reader’s Choice survey will begin next Tuesday, May 1. You’ll be able to vote at!Ebest. Many of you may know that Mardon has won Best Jeweler of the Inland Empire for 9 years in a row. Let’s go for 10!

In the coming weeks, we’ll keep you posted on new happenings at Mardon. Speaking of happenings, the 4th Canyon Crest Towne Centre Craft Beer Walk is on Cinco de Mayo! We’ll be featuring local craft beef from Euryale, one of Riverside’s award winning small brewers.

Marcus & Company Art Deco Ruby & Diamond Brooch

March 17th, 2018 by James L. Sweaney, CGA, FGA. GG

Art Deco Pin by Marcus

Just acquired: this sweet little Art Deco brooch. During the buy, we noticed a serial or stock number engraved on the back, but didn’t see a quality or maker’s mark. The piece tested to be 14K white gold,and was set with Old European cut diamonds and a fine natural star ruby, so we were happy to to purchase it. Afterwards, examining the pin more carefully, we spotted a maker’s mark on the pin stem– “Marcus.” We purchase vintage and antique jewels by Tiffany, Krementz, T.B. Starr, Whiteside and Blank, and other famous American makers, but this was our first piece by Marcus & Company!

Marcus Maker’s Mark

Marcus maker’s mark closeup

Marcus & Company was one of the elite American jewelry houses. Classically trained in the European apprentice system, Herman Marcus immigrated from Germany to New York in 1850 and started working as a designer at Tiffany & Co. He left Tiffany in 1864 to form a partnership with Theodore B. Starr, Starr & Marcus. After Starr & Marcus dissolved in 1877, Herman Marcus returned to Tiffany. In 1884, he joined the firm of Jaques & Marcus, of which his elder son William Marcus was already a partner. George Jaques retired in 1892 and the firm was renamed Marcus & Company. Herman died in 1899, but his sons continued to run the business well into the 20th century. The firm was sold to Gimbels in 1941 and merged with Black, Starr, and Frost in 1962

Marcus & Company was famous for meticulous craftsmanship, for the use of unusual gemstones and fine enameling and for innovative designs inspired by the French Art Nouveau movement. Marcus & Co. jewelers worked in the Paris workshop of Rene Lalique to learn the art of enameling. Throughout the late 19th and early 20th Century, Marcus & Co. was responsible for some of the most unique jewelry created by an American jewelry house. Marcus & Co. pieces are rare and highly collectible.

The combination of gem materials in this pin is unusual and interesting. The carved and frosted rock crystal quartz flanking the center was in keeping with the “camphor glass” look that was all the rage during the 1930’s. The soft white quartz contrasts nicely with the bright red center, a natural cabochon star ruby. The inclusions in the ruby produce a weak star and prove it to be unheated and from Mogok, Burma. The color is vivid violetish red, known as pigeon’s blood red. Old European cut diamonds finish the ensemble of gems and brighten the look.

Besides being the pinnacle of Art Deco styling, the 1930’s were also the Golden Age of Aviation. This pin reminds me of an airplane propeller. My father learned about airplanes and became a pilot during the 30’s, so this piece goes into my personal collection for a couple of  good reasons.

At Mardon, we buy estate jewelry on a daily basis, so we always have new and interesting things to show. If you have jewelry you’d like to sell, please give us a call. We’ll be happy to verbally appraise your items– no fee will be charged if you sell us your items. We buy for cash or trade for store credit. For high value items, we offer consultation and assistance for selling at auctions by Sotheby’s, Christie’s, and other prominent auction houses.  We’re open Tuesday through Saturday, 10 am to 5:30 pm– Please call for an appointment.

GIA iD100 Diamond Tester at Mardon Jewelers

March 3rd, 2018 by James L. Sweaney, CGA, FGA. GG

Mardon Jewelers just acquired the latest diamond testing device from the Gemological Institute of America, the GIA iD100. This desktop instrument uses spectroscopic technology to separate synthetic and imitation diamonds from natural diamonds. The GIA iD100 was developed to inform and protect both jewelers and consumers.

Because of recent technological advances, laboratory grown diamonds are now widely available in sizes suitable for jewelry. Synthetic diamonds aren’t easily identified by normal gemological testing. Most companies label their product with laser etching on the girdle, but unmarked stones are showing up in the market place, posing problems of disclosure.

For centuries, natural diamonds have been valued highly because they are beautiful, durable, and rare. Synthetic diamonds are now being mass produced, so they are not rare. Since synthetic diamonds usually sell for about one third the price of natural diamonds, it’s very important for jewelers to know what they are selling and for consumers to know what they are buying.

The GIA iD100 gives very straightforward results quickly and can used to show consumers whether a diamond is natural or synthetic. Over 98% of natural diamonds are type I while all colorless synthetic diamonds are type II. The tester recognizes the luminescence of type I diamonds and gives them a “Pass”. Synthetic and imitation diamonds generate a “Refer” signal, meaning further study is needed to identify the stone. Type II natural diamonds also referred, but these are very rare. Gemologists usually identify type II natural diamonds by natural inclusions and other characteristics.

As part of our appraisal and buying services, Mardon is proud to offer the latest methods for evaluating jewelry and gems. Even though new technologies like the GIA iD100 are very expensive, we know these investments are worth it in the long run. By keeping up with these new developments, we’re able to offer the best merchandise and expert services available to our clientele.