I love the shine of UTEE (Ultra thick embossing enamel) and it's quick hardening. Bubbles are easily removed and the resulting surface is very smooth and glass like. It can be reheated and melted again if you're not satisfied with the results. On the downside, it isn't very scratch resistant. There's also a product called UTEE Flex, a resin, which is supposed to be added to melted UTEE to give it more durability. Some of the pendants in which I used this product showed cracking if they were not gently handled. I don't know if this was due to excessive reheating, not enough flex added, or just a brittler product over time.
Diamond Glaze, takes 24 hours to set properly, and continues hardening for days. Tiny bubbles can be a problem if you're a perfectionist like me! Pendants sealed with this product became quite scratch resistant over time. It's not quite as clear as UTEE. They did not have a crystal clear glass like finish.
I tried using UTEE to set the picture in place with a nice glassy coating, then applied a thin layer of Diamond Glaze for it's hardness. I wasn't completely satisfied because of the few tiny bubbles I always ended up with in the Diamond Glaze layer. (I did say I was a perfectionist!) For the present time, I'm just sticking with the UTEE. Any one have any suggestions?