aquamarine rough - rough gemstone value
aquamarine rough - rough gemstone value

How to Estimate Rough Gemstone Value


Can you tell if gem rough is too expensive? Learn how to estimate rough gemstone value by considering your gem yield and the prices for your faceted pieces.

2 Minute Read

Sometimes, we gem cutters complain about the cost of rough gemstones. Before you complain, you should consider a few things. When you see a piece of rough and learn its price, ask yourself: "What can I make on this piece of rough after I cut it?" Then you can estimate the rough gemstone value and decide if it's worth the price. Let's walk through an example using a very nice piece of rough aquamarine I had for sale.

Sticker Shock

Very seldom do I see aquamarines of this quality and size. This piece had a good, solid medium-blue color. Other than the growth line and a little spot next to it, this crystal was also clean. It will cut some very large, quality stones, perhaps best as Barions.

  • aquamarine rough - rough gemstone value
  • aquamarine rough - rough gemstone value

    A large aquamarine crystal from Pakistan, 186 cts, 26.5 x 54.8x 11.2 mm.

    In 2001, I sold it at $12/ct for a total of $2,232.

    Does the $2,232 give you sticker shock? Well, it might but it shouldn't. Here's why.

    Estimate Your Cost per Finished Carat

    First, inspect the rough and determine its quality. This was a good quality piece. Next, figure out what it will yield. This piece should yield very high in just about any shapes you want.

    Let's estimate a finished gem yield of 30% (a conservative figure for this piece, in my opinion). 30% of 186 cts will equal 55.8 cts of very nice, clean aquamarines.

    So, $2,232 divided by 55.8 finished carats equals $40/ct. That's your cost per finished carat. Of course, this doesn't count wear and tear on your laps. However, unless you're very hard on your laps, wear isn't that much of a factor.

    Estimate Your Price for Your Finished Gems

    Now ask yourself, what would these finished aquamarines sell for?

    The size of finished stones does affect price, and larger stones always bring higher prices, especially clean stones and matched sets. This crystal should yield stones in the 10-30 ct range, maybe larger or smaller depending on what you cut. (I'd shoot for around the 15-20 ct range).

    Let's say finished aquamarines in this size range and of this quality sell for $80/ct wholesale. That's a real bargain.

    So, at wholesale, you've basically doubled your money. $80/ct times a finished yield of 55.8 cts equals $4,464. If you sell your gems at retail price, you'll likely make quite a lot more.

    Still think this rough is expensive?

    Focus on What You Can Make… and Cut

    In order to calculate rough gemstone value, always ask yourself: "What can I make on that rough?" Don't worry about what other cutters are making. Worry about what you're making.

    Always do the math before you assume gemstone rough is expensive. You may be surprised.

    Also, think before you cut. In this article, I walk through how I would cut this aquamarine for both the best yield and color.


    Jeff R. Graham

    The late Jeff Graham was a prolific faceter, creator of many original faceting designs, and the author of several highly-regarded instructional faceting books such as Gram Faceting Designs.

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