Traditional polishing methods for lapis lazuli is indeed tin
oxide on leather. Other metal oxides have been claimed superior,
chrome is the messiest, aluminium the most expensive, cerium the
cheapest. They all produce the trade mark lapis polish…orange
peel however slick.
This effect is because lapis is not a rock, it is a collection
of rocks with a great affinity for one another such as azurite,
lazulite, calcite, pyrite etc., in varying quantities all with
different hardness, toughness and polishing characteristics.
Sometimes the right combination of exposed minerals allow a metal
oxide technique to produce a high polish this is seldom a
transportable experience. Diamond on a hard surface however
will always provide a high polish as no undercutting of the
softer elements occurs. Although this is technically a 'scratch’
polish you will see a sharp reflection in the surface.
To negate everything I have told you I should add that I have
faceted several pieces of high quality lapis with spectacular
results. Various rose cuts (crown facets only, flattened back to
girdle dimension) round and rectangular as well as pyramids.
Lapis takes an extremely high reflective glossy polish when
faceted. I use a tin lap with aluminium oxide (Linde A) to
achieve this. You also get a premium price for your unique
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