What is a Built-Up Diamond?

January 22nd, 2011 by James L. Sweaney, CGA, FGA. GG
A Built Up Diamond

A Built Up Diamond

These days, we buy a lot of jewelry, used as well as new. Today, I worked with a young lady, a bit down on her luck and on the rebound from a relationship that didn’t work out. She was looking to sell her white gold solitaire ring that was set with the one carat round diamond graded on the cert above. After looking at her stone, I had to tell her that even though the stone had a GIA diamond grading report and the color and clarity were perfectly acceptable, I wasn’t interested in buying this particular diamond because of the poor cut.

This stone is what I call a “built-up” diamond, meaning that it weighs much more than it should for it’s apparent size. It’s important because although diamonds are sold for their beauty, they are always valued and priced by weight. In other words, this diamond looks like a diamond weighing only 9/10 of a carat but costs like a diamond over 1 carat. The consumer lost.

The clues to this problem are readily apparent on the GIA diamond grading report. To a gemologist, numerous measurements and grades show us immediately that this diamond is heavily cut. Let’s dissect the report to see what it really tells us.

First, the diameter, 6.06 – 6.18

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2 Responses to “What is a Built-Up Diamond?”

  1. Brian Says:

    Excellent information! One question, in a case like this would it be possible to “fix” the diamond by re-cutting it or is the added expense just not worth it?

  2. James L. Sweaney, CGA, FGA. GG Says:

    Very good question, Brian! In some cases, you can “fix” the diamonds by recutting, but you have to do a cost vs. benefit analysis.

    In this case, two factors dictate against recutting it. First, the weight of the diamond is only 1.01 cts, so the cutter has nothing to play with– by going below the one carat, the diamond is automatically devalued by 5-10%.

    Second, the quality of this diamond is borderline for recutting– if the stone was VS and colorless, recutting could improve the beauty significantly, so the equation would be more beautiful vs less weight and more cost.

    We often recut/repair damaged diamonds– even though diamonds are the hardest substance on the planet, like any gemstone, they are brittle, and can be chipped. Old European cut diamonds are especially prone to damage because in those days, the cutters usually made very thin girdles (outer edge of diamond).

    It really takes an experienced gemologist to make this analysis, and even then, we usually consult and defer to our cutter’s opinion.

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