The most* 'elvish' ring I own is the one I bought in a pawn shop the only time in my life I have ever been in a pawn shop (pictured below):
As you can see, it is plain metal; no gems. It looks like two leaves. Very art nouveau. Obviously, it's not silver, but you could make something like this in silver, if you wanted to.
Since we're going to have Celeborn wear the ring originally intended for Amarië, it's important that we make it unisex. So, plainer is better. But considering what sort of jewelry Tolkien's male characters (both human and elf) are clearly comfortable wearing, I'm not sure a 'masculine' design is necessary.
*I must admit that I do actually own a plain silver band with two names etched into it in Tolkien's runes, a gift that was certainly intended in the same context as what we're discussing with Finrod/Amarië and Galadriel/Celeborn. So, uh, when I say 'most' elvish, it's obviously a matter of opinion.....