How We Grade Our Rough
I’ve been thinking a lot the last few weeks about writing a blog post which explains the process and terms we use to describe our stones. No better time than now so here goes.
It seems there are as many ways to describe a stone’s clarity as there are types of stones! So, I’d like to start out by briefly mentioning some of the ways I’ve seen rough graded and explain why I don’t use those terms or methods. Sometimes it’s due to personal preference, while other times, I feel it’s a misuse of terms.
“Loupe Clean” Hardly any rough can or should be described as loupe clean. Why? Rough comes with a plethora of textures ranging from thick skins to crinkly skins to sandblasted texture to smooth or glassy - and that is naming just a few. Rough also comes with endless surface anomalies: divots, crevices, creases, peaks, sharp edges, ad infinitum. While a piece of rough can obviously be loupe clean, all of the above means that unless a window has been polished,
it’s near impossible to get a good enough ‘look’ to make that diagnosis.
Speaking of loupes, I don’t use them for grading rough. This is a personal preference. The rough surface conditions mentioned above work to limit my vision when using a loupe. Focused, intense light and my ability to manipulate the stone within the light source is the method that works best for me. Loupes are best used for faceted gemstones.
“GIA clarity grades, VVS, VS, etc.” I do not use these terms to describe rough. They were developed to describe faceted gemstones and frankly I don’t feel applying them to rough is appropriate or even possible. Until rough has been faceted, or at least had a window polished, it just isn’t possible to make such a granular observation.
So, what is my process for grading rough? I usually use an Opti-visor with a 5x magnification lens while wearing reading glasses - so my usual set up is 6.5x magnification. I find this works best for limiting eyestrain while still getting a good look. If I think I see something significant, I’ll switch the 5x for a 10x. I use a specialty yellow light, or torch, with a focused beam. I’ve used
many light sources over the years, including an expensive dental light but found the beam too narrow when grading more than just a few stones. I also used a powerful LED white light for a long time and while I felt it worked well, I have since changed to the light I use today: a Noble Flashlight which was developed for use with rubies and sapphires. I find it is by far the best light I’ve used. We have sold these lights in the past on our website, and will again, once Covid-closed borders open up and we are able to re-stock.
I often describe rough as “clean” which means I didn’t see any inclusions after careful study. The rough may facet “loupe clean” or VVS, but until the actual cutting happens, it’s just not possible to say with 100% accuracy. To say otherwise would not be honest. We get the occasional piece of rough that has a naturally polished smooth surface without too much saturation and those stones are easier to predict. But anyone who’s worked with rough and
gemstones long enough knows that surprises are the norm.
Another term we use often is “eye clean” or “eye-clean or better.” These terms can have several meanings in my process. It could mean that the surface texture or saturation is such that I can’t say with 100% confidence that there isn’t a small bubble or fibrous silk hiding in the stone. But since I couldn’t see it, I believe it will most likely facet eye-clean or better. In general, it has to be pretty small for me to miss. Other times, I actually do see a very minor inclusion - it is natural rough after all - but my experience as a gem cutter tells me that the inclusion will most likely not be seen by the unaided eye after faceting. At the end of the day, these are
judgement calls, and again, it is my experience with faceting that really aids me in reaching these conclusions.
“Will facet with visible inclusions” means just that. We won’t sell faceting rough with cracks or rough that we feel is structurally compromised but many folks find inclusions beautiful and sometimes they can add sparkle and personality to a gemstone. Umba Sapphires and a few other species that are almost always expected to have some level of inclusion, I’ll describe on a gradient: AAA 95+ clean, AA 90% clean and so on. Often rough will have surface inclusions that
will be removed during the preforming stage and that will be noted in the description. If the inclusion is on the table side, we might say that yield will be reduced but a clean stone is possible.
That’s about it for how I grade our stones. The longer I’ve done it, the more I’ve come to appreciate the patience and skill involved. I often need to take second and third look before I have the confidence to post the stone. Other times I flat out miss things. In those cases, we are always anxious to take those stones back and make things right with our customers.