I did, yesterday, when I had to replace a watch battery. I saw this guy painstakingly embed diamonds into a watchband with some type of petrol on the back of his hand. In the same basement, you could design your own ring by sketching it, or improvise preselected molds.

This guy is cleaning some gold chains with a very high temperature steamer.

Fadi is the jewelery designer that designed my friend's and his wife's rings.

Dormar Jewelry
55 West 47th Street
New York, NY 10036
Talk to Fadi in lower level booth #550 or Albert in middle level booth #20

It took 5 minutes to change the battery and pretty reasonably priced too.