Posted 05/30/2011 05:27 am
Luster (or lustre) has a slightly different meaning with different materials.
I am a gem cutter (facetor). I love cutting Australian yellow sapphire. That stuff, when polished with 50,000 or 100,000 grade diamond grit, has a high lustre, but diamond itself has a higher lustre or is more reflective than sapphire because it is a harder material. The degree of lustre on a highly polished diamond facet is described as 'adamantine'.
Although silver is much softer than sapphire or diamond, MS 65 silver coins attract the eye for different reasons. When a coin is struck, there is a general flow of metal from the centre of the coin to the rim, giving the coin a radial cartwheel effect in the fields, and is interrupted by the design details. The effect can be more attractive to some peoples' eyes than a polished proof finish.
With a polished proof finish, the planchet and the die are both polished before being fed into the minting press. That smooth finish explains why there is no radial mint lustre on a proof coin.
Obviously, wear can very easily affect this rather attractive appearance, and that is why MS 65 coins are so scarce, and why proof coins are not meant to be circulated.. It also explains why sapphire and diamond need to be so hard when they are used in jewelry.
I am a gem cutter (facetor). I love cutting Australian yellow sapphire. That stuff, when polished with 50,000 or 100,000 grade diamond grit, has a high lustre, but diamond itself has a higher lustre or is more reflective than sapphire because it is a harder material. The degree of lustre on a highly polished diamond facet is described as 'adamantine'.
Although silver is much softer than sapphire or diamond, MS 65 silver coins attract the eye for different reasons. When a coin is struck, there is a general flow of metal from the centre of the coin to the rim, giving the coin a radial cartwheel effect in the fields, and is interrupted by the design details. The effect can be more attractive to some peoples' eyes than a polished proof finish.
With a polished proof finish, the planchet and the die are both polished before being fed into the minting press. That smooth finish explains why there is no radial mint lustre on a proof coin.
Obviously, wear can very easily affect this rather attractive appearance, and that is why MS 65 coins are so scarce, and why proof coins are not meant to be circulated.. It also explains why sapphire and diamond need to be so hard when they are used in jewelry.
