Set of five hardness pencils.
Each 'pencil' has a tip of a different hardness from No.5 to No.9 on the Moe scale of hardness (see 'Further Information').
Is it easy to use?
See which will scratch your sample and which will not.
Hardness varies from sample to sample, and it can also be different in different directions.
These are for testing minerals, e.g. out in the field. They are not suitable for use on cut gemstone (jewellery) - you scratch the stone, the stone becomes worthless and/or your customer sues you.
The Moe scale of hardness goes like this: