Helidore Facet / Faceting Information
Color: yellow, yellow/green Moh’s
Hardness: 7.5-8 Refractive Index: 1.57-1.60
Critical Angle: 39.97°
Specific Gravity: 2.65-2.75
Fracture: Conchoidal, tough
Dispersion: .014 Heat Sensitivity: Slightly
Dichroism: weak (gold-yellow to greenish-yellow)
Birefringence (double refraction): Weak (.006-.009)
Crystal Structure: Hexagonal
Treatments: Often heat treated and irradiated.
What I prefer to polishing with: Cerium oxide with a Spectra Ultralap.
Jeff’s Comments: Cuts and polishes like any other Beryl, usually no problems. I like to use a 1200 Nu Bond lap for pre-polish, it makes the polishing stage faster and easier. Orientating on the “c” is slightly better. Watch for silk and lilly pad type of inclusions perpendicular to the “c” axis.
Design Notes: About any design will work well. I prefer a deeper design and often cut Barions.