I’ve done this for a small job 5 years ago it was time consuming but doable.
I painted the fret cut letters and I had a tray with all the gems in facing face down then I placed the glue painted side onto the gems they all stuck but as you can guess I had turn the ones that needed turning. I realised after though I could have used any double sided cheap gems style crystals which would have been way easier. I used a epoxy clear acrylic resin. Worked a treat. I’ll try and dig out a photo for you.
If I was you do a a earch for cheap gems if you could get a chrome fret cut letter then painted the clear glue then the gems it would make the gems pop because of the chrome shimmer affect behind the clear cheap gems.
Hope it makes sense 😉