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
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.
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.
Basic Business Rules: Buying Rough
Tucson Gem Show Dates 2006
Barion Cut Designs for Colored Gemstones
Digital Faceting Machine
Eight Famous Sapphires and the Stories Behind Them
How to Dry Opals Safely
Rose Quartz Value, Price, and Jewelry Information
Ten Big, Beautiful, and Affordable Engagement Ring Stones
When you join the IGS community, you get trusted diamond & gemstone information when you need it.
Get started with the International Gem Society’s free guide to gemstone identification. Join our weekly newsletter & get a free copy of the Gem ID Checklist!