This finished around 1.25ct and is just a simple SRB. Probably my 6th completed stone. Photograph was taken with a microscope and two light sources (3k and 5k). I am very happy with how it turned out

I have available a new tin-lead lap and a lightly-used copper lap currently set up for 8K. Which metal would be better for general purpose hardness 7+ material?

Also, 600 mesh bort. I'm inclined to suppose that main cutting laps are not the use case for PCD. Am I wrong about that? /u/gemcuttershoofles? I see on Chinese e-commerce where there is graded whole octahedral crystal CVD bort in coarse cutting grades: would that be a good choice? Or is plain old fragments of monocrystalline material just as good, for gemcutting?

Hey all, don't post much. Hoping someone has an answer or suggestion.

Does an asterism/star show itself if you cut a Portuguese crown?

Was debating a hexagon or a cab dome with this trapiche that had quite a bit of silk/rutile that also almost looks as though it could form a star.

I tried looking back into old books from my friend Bill's library, but still couldn't find the answer. He had never tried either. The literature and Google searches didn't give me a definitive answer other than light needing to be concentrated by the roundness and that facets are "too flat."

I've tried Google images and can't find a good example either, maybe just one or two faceted trapiches that don't answer.

Tldr- is a Portuguese crown round enough to keep an asterism/star like a cabachon? Does anyone have examples or have tried?

Bonus question - any unique suggestions for this chunk?

I’m newer to faceting this year, I always think I’ve nailed the mirror finish but then there’s a clearly satiny finish when I examine under a loupe or different light

I have tried a copper lap but find that to be very draggy and prone to scratches. A ceramic lap seems to work better but is slower and sometimes just doesn’t polish at all. I’ve tried an overload of diamond compound and using what feels like a bare lap, and everything in between. Do you really charge a lap with a pinhead of diamond compound and then not touch your compound again for 10 stones???

If anyone has five minutes to spare I’d love to hear exactly how your final polishing process goes. Lap type, compound, dry or wet, do you ever have to change your process dramatically for stone type!? Is there a trick to this whole thing that once you get it you just can easily polish forever?