There are a couple of somehow strange variants of art, one of them is gem paintings where the colors are substitutes by a variety of gems with the necessary colors. Means ruby and spinel for red, jade for green and others by semi precious stones.
Naturally they wont take the best gems for this wall decoration, this is not necessary anyway but because of the nature of the material it’s not cheap stuff either. This are not the finest stones which are taken to “paint” but the idea are not the value of the stone but the composition with the stone.
Some are with rich colors
some not it just depends on the picture made. Almost all gems used are heat treated means melting away some of the inclusions that is common.
There can be a very interesting effect on such a “picture” since rubies fluoresce under ultra-violet light and some even in daylight and if these are synthetic stones they even fluorescence very strong. Imagine you have such a painting in the house set a small UV light somewhere and get your decoration shine.
Although most buyer don’t think about this it gives a somehow unique effect.
All this looks a bit like impressionistic painting because of the nature of the material which also won’t make it fit for small details. That resulted in a rather loose and brightly colored painting. It is necessary to learn some fundamentals of this variant of painting to get the most out of it.