Conversation so far:
When did Diana Princess of Wales get engaged?
Charles, Prince of Wales, proposed on 6 February 1981, and Lady Diana accepted, but their engagement was kept secret for the next few weeks.
Does the article mention Diana Princess of Wales's engagement ring size or kind of stone?
Diana, Princess of Wales, selected an elegant, large £30,000 engagement ring, consisting of 14 solitaire diamonds surrounding a 12-carat oval blue Ceylon sapphire set in 18-carat white gold.

Question: Who made the ring?
Self-contained rewrite: Who made Diana, Princess of Wales' engagement ring?