it's everything I love about oriental art, each part beautifully done and thought out, the intricacy of the detail and in such a small little piece. Reminds me of oriental embroidery really.
I've done some tentative searches and I think found something similar so they maybe still make these pieces or similar using this sand blasting technique.
This site shows some more recent products where they've used a vine/ivy decoration on sake cups and bowls. http://www.japanartsandcrafts.com/otaruglass.html
They've used some form of stencil or mask as the designs repeat sort of with the interior blue picking up the same shapes as both the amber and red flowers. It seems to have been made in at least 4 colour layers if not 5 maybe, with blue then clear then yellow , amber, red.
Something I've read (might have been something I read from Kelsey Murphy's work) seems to say if I've understood it correctly, that maybe blanks can be made by rolling the original gather in powders rather than casing, then reheating and rerolling in different colours to create the layers. Does that seem feasible?