Gem powders VS Mica powders

I think it is Mehron the gem powders..What do you think of them....What I am looking for is a sheen not sparkly like glitter. When I do a tiger for instance I use metallic white for the white areas and I would like a sort of sheen over that area to add a fairy tail look. Any suggestions?

ok I watched Jenny on Faba. Precious gems diamond is a shimmer then the Pearl has more of a satin look this is better at the mussel area the Diamond is everywhere else...
Are the gem powder and the mica the same results?

I don't really like them, I use the on top of paints to make it shimmer but it tends to opaque and hide the base color, I prefer the BEN luminaries.