I did some online dictionary work on this the other day. There are two "schools" of thought on the words. School 1: According to Oxford & Webster, opaline and opalescent are synonyms. School 2: Some smaller online definition sources have that opalescent means having colorful iridescence. (The trouble here is I found a couple of things that mentioned this for opaline. :help:)
I think I will personally use them as synonyms. If it's good enough for Oxford and Webster, it's good enough for me. I do reserve the use of the "o" words to glass that is milky with an opal appearance. I call the pure white glass lattimo or milk glass. (Or if it is colored, I call it colored lattimo or milk glass.)
I'd like to get a person who understands glass chemistry to comment. Where are our glassmasters when we need them?