Grading rough with the finished stone in mind
When we assess facet rough, we consider the finished stone it has the potential to produce, not simply whether the uncut piece looks clean.
Our approach draws on decades of sourcing, buying, sorting and grading material directly from miners. Clear, consistent grading is fundamental to helping buyers choose suitable rough and understand its characteristics before cutting.
We began using VVS-style descriptions for facet rough in 2001. The definitions below explain our own grading system and how to interpret these terms in our listings. They are our assessments of the material, not independent laboratory grades.
Why we describe more than “clean”
Terms such as clean, eye clean and slightly included can be interpreted differently. A description that says only clean does not tell you whether the seller means free of visible inclusions to the unaided eye or something closer to flawless.
We prefer to explain the grade we assign and relate it to the clarity we anticipate in the finished stone. That gives buyers a more specific starting point than an undefined description of clean.
The grades below should be read alongside the individual listing, its photographs and any notes about inclusions or other characteristics.
Our facet-rough grades
VVS–IF
Our clean-to-flawless range. We use this designation to describe rough that, in our assessment, has the potential to produce a finished stone within that range. It expresses our clarity assessment rather than an unspecified clean label.
VVS
In our assessment, the rough has the potential to cut a VVS stone, with no inclusions visible to the naked eye in the anticipated finished result.
VS and VS–VVS
Our eye-clean descriptions: we anticipate a finished stone with no inclusions visible to the unaided eye. The specific grade and any accompanying listing notes communicate our assessment of the individual piece.
VS–SI
Eye clean to slightly below eye clean in the anticipated finished result. This sits between our eye-clean descriptions and slightly included material.
SI — Slightly included
Material that we assess as suitable for faceting but with inclusions that may remain visible in the finished stone. We expect their effect on its overall clarity to be relatively limited rather than dominant.
Examples may include visible spots, strong needles, slightly stronger silk, a veil inclusion or a very slight crack. Some features may be noticeable under a strong overhead light without standing out strongly in the finished stone. The type, position and visibility of inclusions vary, so please read the individual description carefully.
Included
Material with visible moderate to strong inclusions. These may include cracks, large spots, large crystal inclusions or other prominent features. Consider the particular stone’s description and your intended use rather than the grade alone.
An assessment of potential, not a guaranteed cutting outcome
Our grades express our experienced assessment of the rough and the clarity it has the potential to achieve after suitable cutting. They do not guarantee a particular finished result regardless of cutting decisions or the characteristics encountered while working the material.
If a particular clarity result is essential to your project, contact us before purchasing. We can discuss the actual piece, the inclusions described and the basis of our assessment.
Why we do not use “80% clean” or “90% clean”
We find percentage-based descriptions too vague to explain facet rough clearly. Does 90% clean refer to the proportion of the piece without inclusions, its appearance or a prediction about the finished stone? Without an explanation, the buyer is left to interpret it.
Dealers visiting Arusha have asked us over the years why we use VVS-style terms rather than clean, eye clean or percentage descriptions, particularly when material is sold in lots. Our answer is that a defined system, supported by descriptions of the actual material, is more useful to us and to our customers.
We do not expect an undefined clean label to mean the same thing to every seller or buyer. Experience and interpretation differ, which is why explaining our own terminology matters.
Selection is part of the service
We examine large quantities of rough at source and select individual pieces for our website. The work includes sourcing, sorting, assessing quality and considering suitability, not simply attaching a grade to everything offered to us.
For you, that means access to selected rough and the opportunity to ask us about it without travelling to the mining areas or sorting through masses of mine-run material yourself.
Clarity is only one part of understanding a stone. Read the listing’s weight, origin, treatment information and other characteristics alongside its grade. We specialise in natural gemstones with full treatment disclosure; natural does not automatically mean untreated.
Questions and discussion are welcome
If you would like more information, want to discuss a piece of rough or have thoughts about grading, please get in touch. Include the listing link so we can talk about the exact material.
The gemstone community is closely connected and built on trust and respect. We value the conversations and long-term relationships that make buying and working with gemstones rewarding.
Email: info@gemsofeastafrica.com
WhatsApp: Message us on +44 20 8144 4017
Telephone: +44 20 8144 4017
Ali
