People who wear necklaces would want to see the item. And the dark fourth century coins can be a challenge. A good cheap starting place might be a lot of larger byzantine follis coins with Christ, a Cross, or/and the latin letters saying in greek Christ is King of Kings. You'd have to shape the bezel by hand as they are not at all round very often like the one in your example. And you'd have an easy to read 1000 year old Christian relic in some respects. (I realize it is not guys, but it would be way to think of it as it is a picture that is 1000 years old.) See the examples below.https://www.acsearch.info/search.html?id=3304503https://www.acsearch.info/search.html?id=5188886
And all the auction houses have these lots for sale. But you need big easy to see coins. You can also sometimes get some low grade but obvious large horse coins of Carthage that might be nice.