So last week I was having this issue with worrying about my veil because it was much darker than my dress and it was very noticeable. I have a single layer cathedral length mantilla veil. I did a little bit of research and decided to try Oxy-Clean after being turned away be 3 different dry cleaners who couldn't help me. Last night I dipped a part of the lace into a mix of warm water and a half cup of oxy-clean and let it sit for 3 min. I then pat dried it with a towel and the color came right off and left a slight hue to the lace so it's just the right color! I'm so happy considering I was stressing out about having to buy another veil =/
Anyways, for anyone who may have this issue, Oxy-clean is a great product! It didn't ruin the lace and didn't really do anything to the veil itself either. I think the veil may have been dyed with tea and the oxy-clean was just cleaning off the tea stain. I hope this helps someone in the future who may encounter the same dilemna!