Case Study: Recutting A Commercial Cut Morganite

Some time ago I acquired a large pale pinky-peach 7.5 carat morganite from a gem dealer overseas. Due to a moderately sized window in the center of the stone, as well as a deep pavilion that would make wearing it difficult, I knew that the stone needed to be recut. 

The Diagnosis:

Before putting the morganite on the dop stick, I took a closer look at it to see the symmetry of its facets, as well as how polished it was. I found the typical signs of commercial cutting:

1. The Window: The pavilion angles were simultaneously too steep and too shallow, with the facets higher up too steep, and the angles at the bottom too shallow. The bottom angles are what allowed light to leak out the back. The edges of the stone looked alive, but the center appeared lifeless.
2. Polish: Appears to have received 14,000 diamond grit, which results in noticeably less reflection than the 50,000 to 100,000 diamond grit that precision or competition cutters use. 
3. Symmetry: The facets didn’t meet at points, but the overall symmetry wasn’t too bad.

(If you want to understand the importance of pavilion angles, read our guide: Precision Cut vs. Commercial Cut Gemstones: What You Are Actually Paying For.

Cutting for Light Performance:

To close that “window” and make the entire stone sparkle, I had to grind away a good portion of the bulging pavilion. Commercial factories don’t do this as they are paid by the carat weight, retaining weight at all costs, often creating misshapen stones or allowing light to pass right through them.

The Trade-Off:

• Starting Weight: 7.5 carats
• Recut Weight: 4.76 carats
• Yield Loss: 36.5%

The particular recut is a good example of how much weight can be lost from seemingly minor adjustments: The stone lost almost no size to its diameter – just a few hundredths of a millimeter. The 36.5% weight loss was all contained in the overly large pavilion.

The Reveal:

After hours of cutting and polishing, the stone was finished.

The “dead” center is gone. It has been replaced by a bright color that travels edge-to-edge. The stone’s diameter is the same as before the recut, but it appears larger because it is returning light to your eye rather than letting it leak away.

The Stats:

• Final Weight: 4.76 carats
• Design: Custom old mine cut grown, with modern pavilion
• Performance: High light return

Conclusion

When looking for a gemstone to wear in a piece of jewelry, quality of cut shouldn’t be overlooked. It is the most important factor. You can have the best color in the world, but a bad cut can make it look dull and lifeless, whereas a precision cut can bring it to life.