Saffordite an Arizona Gemstone!
Tackling Saffordite: Engineering Light Return and Polishing Arizona Glass
When a local client brought in a piece of Saffordite—a rare glass-like material found only near Safford, Arizona—I knew the bench work would present an interesting challenge. Cutting natural glass isn't inherently difficult from a technical standpoint, but optimizing its optical performance certainly is.
The Design Dilemma: Low Refractive Index & Ring Depth
The primary challenge with this piece came down to optics and proportions rather than lap mechanics. Testing this specific rough in the lab yielded a refractive index (RI) of 1.47—right on the lower end of the spectrum for Saffordite.
Light Return: Materials with an RI of 1.47 require steeper pavilion angles to avoid windowing and achieve strong light return.
The Wearability Problem: Steeper angles mean a deeper gem. Because the client wanted this set into an open-backed ring, a standard deep pavilion would protrude too far down and poke the wearer’s finger.
The Solution: I modeled the gem in Gem Cut Studio to optimize light performance while closely measuring the ring's mounting depth. We settled on adding a culet facet, which flattened out the absolute bottom of the stone without sacrificing brightness or poking through the setting.
The Cutting & Polishing Progression
The rough was cut using a standard sequence on a BATT lap:
Pre-forming & Shaping: 250 grit
Fine Faceting: 500 grit
Pre-polish: 3,000 grit
Final Polish: 60,000 diamond grit
During the polishing stage, the material exhibited the classic sub-surface hazing typical of silicate glass. While many lapidaries default to oxide polishes like cerium oxide for glass, I prefer staying with diamond for faceting because it provides vastly superior control, flat facets, and crisp meet-points.
To eliminate the haze on the 60k diamond lap, the fix was simple: drastically charging down the lap. By reducing the amount of diamond compound on the BATT lap to a bare minimum, the haze cleared up completely, leaving razor-sharp meets and a mirror finish.
The Final Result
The project turned out to be a complete success: a brilliantly bright center gem tailored precisely for the client's custom ring, accompanied by a matching pair of 3mm Saffordite accent studs for earrings.
