Grading is the most important and critical aspect in the colored gemstone industry and Kariba
minerals understands this fact very well and takes it very seriously giving it all the attention it
deserves. Kariba minerals has a team of well qualified and experienced gemstone sorters, knockers,
graders and quality controllers to ensure consistency in quality customer service delivery. The grading
of Amethyst rough comes with its own challenges just like any other natural gemstone. The purple
quartz variety comes in different shades of Purple and clarity. The Color is from Reddish Purple, Violet
Purple, Purple and Pinkish light Purple. Clarity is from Very Very Slightly included (VVS) to Extremely
Included (I3). Kariba has a standard grading procedure which is as follows.
SIZING
This is the first step in gemstone rough grading before you consider other factors, this process is
achieved by using sieves or screens of different sizes in millimetres (mm). This process helps us
group the stones into different size ranges which makes the grading easier.
COLOR GRADING
In colored gemstones, color is very important and it is the value setter. We grade our stones
considering all its components that is, hue, tone and saturation. Values are assigned according to the
lots.
CLARITY GRADING
This is the second most important factor after color. The stones are graded according to their clarity
using 10x optivors. This helps in making sure that the stones are properly categorized from the very
clean to the most included lot of our rough amethyst gemstones. After considering all the factors the
stones are assigned clarity grades such as very very slightly included to extremely included by
qualified gemologist or gemstone specialists at Kariba minerals.
WEIGHING, LABELING AND PACKAGING
The stones are labelled according to the grades from color to clarity giving them lots such a,b,c,d,e,f
etc The individual lots are weighed in grams (g) or kilograms (Kg) to keep the records for
accountability. The lots are labelled indicating Grade , Size , Lot number, and Weight in grams or
Kilograms.