Mounting and preparing a gemstone or industrial diamond for the formation of a mark on the surface thereof

In order to mount a diamond 7 in a dop 31 so that the diamond table 7a is level and at a predetermined height, the diamond 7 is positioned in an injection moulding tool so that its table 7a is engaged with the underside of a top plate 55, the diamond 7 being pushed upwards by an insert 54. An elastomer 35 is injection moulded into a dop ring 32 and holds the diamond 7 securely in the dop ring 32 in that there is elastomer 35 both in front of and behind the girdle 7c of the diamond 7. Although some shrinkage of the elastomer 35 can occur, the table 7a of the diamond is set strictly parallel to the upper and lower surfaces of the dop ring 32 and the table 7a is just slightly below the plane defined by the top of the dop ring 32. In this way, the dop 31 can be placed on the table of an apparatus for forming the mark by microlithography, after applying a photoresist to the diamond table 7a. In order to bake the resist, the dop 31 is placed over the heater tip 63 of a Peltier beat pump which has a cavity 64 containing a drop of solder, in order rapidly to heat up the diamond 7, control the duration and temperature of baking time, and rapidly cool the diamond 7.