Ruby is at or near the bottom of all possible lists. I don't much like gemstone names in general, and this one is just so down-market.
I knew a very nice, very pretty
Mara at school. Rating it is a problem - fresher than
Mary, livelier than
Maura, probably not quite as nice as
Moira ... very hard to find a nn for it, which I suppose is a plus.
Gwendolen is a good spelling. Turning -len into -line or -lyn is awful. I'd put it pretty low on a list of Welsh names as far as actual use is concerned, but I think that could be from associations with Gwendolens I've known. I could face it bravely as a mn on someone else's child, but I wouldn't use it. Actually, I'd use it before I'd use
Gwyneth! But not in this lifetime.