Take horn as is used to make lanterns, quite thin, and underneath imitate your jasper, cornaline, and other stones. That will look more appropriate than doing it on glass, which is too shiny. And the horn gives a lustre and a fatty polish similar to jasper.
You know how you can imitate roses with scrapings of the said horn. The colors for this jasper need to have as a base clear turpentine or spike lavender varnish. And matte, opaque colors are not appropriate, no matter how fine they are. You have to oil the unpainted underside with spike lavender oil.
at middle top margin of folio 010r
Thin glass looks very fine for this effect
at left top margin of folio 010r
You can inlay beds with it, and on the joints you can throw talc or metal filings on the fresh cement of the said joints. You have to bond them with gum amoniacum soaked in vinegar. To better imitate marbled jasper, apply coarse wool hair dyed various colors and intermingled. After you have laid down all the colors, scrape oblique lines into them then lay down gold leaves and silver leaves. If you lay down colors made of turpentine on the horn, give it a backing of silver leafor of tin leaf. You can also file horn and mix it with strong glue and lay it down onto the joints of the horn piece and finish with a joiner’s plane.