Every masterpiece begins with the raw material. Knowing how to select the right piece of faceting rough separates the casual hobbyist from the professional lapidary. At Jackson’s Gems, we have spent over 20 years grading, evaluating, and hand-selecting rough to bring you only the material with exceptional clarity and yield.
The Jackson’s Gems Standard
Because we are cutters ourselves, our grading process is ruthless. We hand-select our inventory by calculating internal volume and orientating every piece for maximum saturation. If it doesn’t meet the standard for a world-class finished gem, it doesn’t go on our site.
1. The “Window” into the Stone
When you purchase premium rough from us, you will often notice that many pieces feature a small, polished flat surface or “window.” We provide this window purposely. A natural crystallized surface scatters light, making it impossible to see deep into the stone’s heart.
Master Tip: Loupe Inspection
Always inspect the stone through this window using a high-quality 10x loupe. You are specifically hunting for “silk” (fine rutile needles), subtle veils, or microscopic negative crystals. If you spot an inclusion, map it out! Your goal is to orient your design so the inclusion sits outside the intended pavilion or girdle so it is cut away during the pre-forming stage.
2. Understanding the C-Axis (Crucial for Tourmaline)
Tourmaline is strongly dichroic, meaning it displays different colors or shades when viewed down different crystallographic axes. The long axis of the crystal is called the C-axis. In many Tourmalines, especially deep greens and blues, this C-axis can be “closed”—meaning it is so darkly saturated that it absorbs almost all light, appearing dead black.
If you cut a Tourmaline with a closed C-axis using a traditional brilliant pavilion, the ends of the stone will go completely pitch-black and kill the brilliance of the entire gem.
“At Jackson’s Gems, we test every piece of Tourmaline (including our deep Chrome and Sunset varieties) to ensure the C-axis is open enough to facet, saving you from cutting a stone that finishes black.”
3. Geometric Yield vs. Carat Weight
One of the most common mistakes inexperienced cutters make is buying rough based solely on heavy carat weights. A 10-carat piece of rough might seem like a bargain, but if the stone is shaped like a “flat macle” or a thin, platy shard, you will be forced to cut a massive, shallow table with no pavilion depth. The result is a windowed, lifeless gem with terrible light return.
Master Advice
Always prioritize geometric shape over raw weight. A blocky, well-proportioned 5-carat piece of rough will often mathematically yield a larger, vastly superior finished gem than a flat 10-carat shard. Focus on finding stones that naturally accommodate a deep pavilion profile to guarantee a brilliant return.
4. Color Saturation & “Skin” Assessment
River-tumbled rough or raw, frosted crystal faces (“skin”) naturally diffuse incoming light, which can falsely lighten the perceived color of the gem. You must see past the skin to assess the true deep saturation of the material before purchasing or cutting.
The Detergent Trick: If there is no window on the stone, briefly dip the rough in water mixed with a single drop of liquid dish detergent. This breaks the surface tension, coating the frosted skin evenly to mimic a polished surface, allowing you to instantly peer inside.
Better Yet: For serious daily grading, utilize professional refractive indexing fluids like Italdo Refractol Gem Examination Fluid. Plunging rough into a high-RI fluid completely eliminates surface refraction, making the crystal look almost entirely transparent like glass!