I'm sure experts will chime in, but from my experience there's no way to tell sometimes. It's part of keeping rays, I like seeing how rays develop as they mature. Some start out as gems and don't live up to what we originally think they'll be.. others are ugly ducklings and turn morph into amazing looking adults. I've seen thousand island bd pups both with spots already and without. Same goes with eclipse spots, some will hold that donut shape and others wont.. comes down to genetics in my opinion. At the end of the day it's all preference anyways so if you're not happy with how one turns out, do some research and get another! It's all part of the hobby