I mean, it was going to be expensive anyway. It's also not hard to find just gem powder now that I'm thinking about it, because people want big, contiguous gems. So finding a whole or many to make up or encrust a full wedding band? Incredibly expensive. Loading gem powder instead of a dye into resin? Not cheap, but moreso, and less of an artistic statement imho. If you want plain colored crushed crystal, glass/cubic zirconium is an ideal stand in. Like, you can make that idea for relatively cheap, set it in a band of a nice gold/silver, and it would look just as good, because you obviously lose some of the qualities that makes gems desireable in the first place, if the fact they're your birthstones don't really matter. But if you have multiple whole gems to really fill out the band, and the money to really splash out in the jeweler, it could be gorgeous.

So basically, as always, it comes down to what exactly you want, your budget, and how much appearance matters next to what the materials actually are.

Lots of people are doing something close when making bent wood rings. This one for example uses crushed turquoise, but grinding it finer and then laying out a gradient likely wouldn't be that tough.