Emerald Faceting Information

Emerald (Beryl)

Color: Green
Mohs Hardness: 7.5-8
Refractive Index: 1.57-1.60
Critical Angle: 39.87°
Specific Gravity: 2.65-2.75
Cleavage: None
Fracture: Conchoidal, tough
Dispersion: 0.014
Heat Sensitivity: Yes, especially depending on treatments
Dichroism:Weak
Birefringence (double refraction): Weak (0.006-0.009)
Crystal Structure: Hexagonal

Treatments: Almost all emeralds are treated to improve color and durability. Assume that any emerald you see is treated. I personally do not agree with a lot of the treatments used on emeralds. Here is an article on emerald treatments and my opinion on them.

Are all Emeralds treated and what is your opinion?

What I prefer to polishing with: Cerium oxide with a Spectra Ultralap.

Jeff's Comments: I seldom cut emeralds, most of the rough is low quality in my opinion and I do not like to cut oiled, or opticoned rough. If you want to cut some for the color, I suggest cutting man-made emerald.

Design Notes: Mostly emerald cuts and step cuts because the crystals are usually small long and narrow.

Design Links: Signature #4 - This is one of my favorite cuts in beryl
Blue Ice - Designed for very long crystals