That being said, there are excellent, optically-clear, UV stable epoxies that are made for this problem. Hxtal is the go-to for most. https://www.lakesidepottery.com/HTML%20Text/Tips/Hxtal-NYL-i...
It is very thin, and will happily wick in and fill cracks. Often the join is completely invisible. The downside is that the cure time is on the order of 1-2 weeks. It does take a little practice to use effectively, and it's worth trying on less-important projects first, but it's straightforward enough that you can expect success if you follow the directions carefully.
As for the aesthetics. No matter what you do, you don't get a whole piece. It is broken and always will be. What you can do is to create something new that both has the beauty of the old and the care, beauty, whatever of continuing. I don't know how to explain this in logic, but there it is. I had quite a nice ceramic cup with charm that broke. I used black urushi which was not gaudy like gold leaf can be. I liked it even more than before.
Another option is silver leaf instead of gold depending on the glassware. And finally you can get really crazy. Rankaku is where you get little tiny pieces of quail egg shell and place it into the urushi. It is painstaking - to say the least- but the results can be beyond stunning. https://www.pinterest.com/pin/jean-dunand-18771942--55309901...
This is a very advanced and difficult method of glass re-forming.