Vintage Sterling Silver Pink Agate Adjustable Ring

This ring is awesome! The setting reminds me of a castle. I am not sure what the reddish pink stone is, seems to be some type of agate. It’s a very pretty and I guess rare color that you don’t see very often. I did test it, and I took a picture on the tester so you can see the range that it falls in. It’s definitely older. The inside is hand marked 925 and Ind. Arg . I did try to research online. It suggested that it could mean Indian agate, but that doesn’t quite add up to me .. maybe, I have no idea. It is adjustable. It’s sitting slightly bigger than a six right now, but you can expand it to make bigger or squeeze it together to make a little bit smaller… it has a nice weight to it 10.76 grams. It’s really a very unique ring.