Thanks for all the replies.
The blanks were indeed diamond cast blanks although they came from mckenzie pen works in America. The blanks were bought last year as my friends announced the wedding while we were on hols in Florida and I'd seen these blanks on IAP at the time. It was both their favourite colours so was perfect.
The kits were from Taylors Mirfield and just ouze class as they feel a lot more classy than the sierras I normally make, bought at the Harrogate woodworking show~~that's how long I've been working on these as they needed to be perfect.
The engraving ended up being done by a jewellery engravers in Manchester( who pleasantly surprised me by being impressed with the blanks) who did a fantastic job and infilled with silver. But it just wouldn't sit right with me as you could feel the engraving and I wasn't happy with them so I cleaned them out with acetone then proceeded to fill them with epoxy and mica powder. Then very carefully sanded back then polished them.
That part scared me as they were finished and I decided to change them and potentially ruin them.
But alls well that ends well. They came out great I think and I hope they use them, I think they will.