I have 2 sets of 24 chrome metal button backs for sale - brand new. Each set is 10.00. These have a deep "scoop" so you can glue almost any pointy back stone into them from size 20mm to 30mm. I have them shown in the photos with a 25mm crystal stone glued into them. When making a tufted headboard 6 years ago I used these exact same button-backs and I used E6000 glue and the stones NEVER came out of the button backs. Also the loop on the back makes these so easy to sew onto anything, and especially easy to use for tufting furniture. The loops are nice and strong and won't break when pulling them into place with thread or wire.
The button backs themselves measure just under 23mm wide by 7.5mm deep (not including the little loop). With the loop they are just under 10.5mm deep.
You can see in a few of the first photos how great these work to make your own crystal buttons. If you need more of these I can custom order them to be made for you.
I've also included pics of some of the other "crafty" items I have, including some crystal buttons and crystal furniture knobs. All are for sale right now on Craig's List in other listings.