Rough rock for lapidary
Rough rock does not photograph very well and so to indicate texture, colour etc. we have shown some cut stones mostly made from our rough stock.
If the third digit of the code is '0' (i.e.??-0??) then the material will generally be supplied in tumble-polishing size (mostly less than 3cms) but may still require further reduction in size by breaking with a hammer (Wrap stone in sacking to prevent flying 'chips' and also wear protective eye glasses). If the third digit of the code is a '1' (i.e. ??-1??) then the supplied material will be larger pieces suitable for cutting with a diamond saw.
Hardness: use a simple 'scratch test to determine the approximate hardness of a stone. A stone which can be marked with a pen-knife, but not with glass, must have a hardness somewhere between 5 and 5 1/2.
Finger nail. 2 1/2
Broken glass 5
Pen-knife 5 1/2
(Hardness is shown in Mohs units: 10 is hard, down to 1 soft.)