Kulukuluku region of Congo yields some of the best Chrysocolla and Malachite specimens in the world. Perfectly intact material is mostly sold "as is" for specimens with other less perfect material being polished into free forms.
The material occur naturally in thin layers on a grey matrix and can have complex vug like features. Polishing this material into free form is exceptionally difficult, and it is highly unlikely that specimens will have a 360 degree perfect polish. Often sections or one side of the free forms will have matrix exposure. A small % of the polishers prefer to colour the matrix using the natural dying qualities of the minerals thus changing the grey tones to blue green areas.
This short video will give you a break down of what to expect both in terms of natural specimens, but more specifically how the nature of the specimens impact the polishing and working processes of material coming out of the region.
Congo is an exceptionally large country dominated by rural areas. All polishing is generally done by hand. The polishing may be considered to be "rudimentary" when compared to highly experienced and more machine based lapidary work being done in Madagascar.
Video by Nick May