Lapis is realtively soft - about 4 on the Mohs scale. How much
polishing depends on how deep the scratches are-of course.
Someone who regularly cuts and polishes cabs, could probably make
a good guess at what grade of abrasiveness to begin a repolish
job. The more coarse abrasive moves more material faster than a
finer abrasive. Basically, the principle is to use only the level
of abrasiveness that will remove the deepest scratches. The to
work “forward” to finer abrasives to remove the scratches left by
the previous abrasive, until you get to the polish stage.
Depending on the stone, a common final polishing powder is
But since you’re new, you might try this method.
For a stone like lapis, you go “backwards” in abrasivesness.
That is, use the polishing rouge (or better yet zam) and see what
that does. I doubt that you will get the high shine that cerium
oxide provides however. If you’re happy with the results, great.
If not go back a step to tripoli; clean, and move back to zam.
Zam is a little kinder than other polishes to soft stones such as
lapis and turquoise.
If the tripoli doesn’t remove the scratches, don’t go down to
bobbing compound, as that may remove way too much material before
you realize it. Then you’re hosed! Find someone who has lapidary
equipment to do the job for you.
BTW: Lapis is beautiful material, but not a good choice for a
ring worn everyday. You can’t wear lapis rings when ya scrub the
sink! You may want to invest in some cerium oxide powder to put
on a small hard felt wheel in you flex shaft for just this type
of job. Wet the pad and the stone, then apply the cerium oxide to
the pad. Ya don’t need much. A little dab-2 cubic mm is enough
for a small stones.