In Britain the norm, on such occasions, nowadays, is to use a crown from the royal regalia (‘crown jewels’). Thus, at the Queen Mother’s funeral the crown on her coffin was the same one with which she had been crowned queen consort at Westminster Abbey in 1937. Elsewhere, however, special funeral crowns were sometimes made. For example, at the Basilica of St Denis, in Paris, you can still see the special funeral crown made in 1824 to be carried on the coffin of King Louis XVIII.
For the reburial of Richard III, it would be difficult to use a crown from the royal regalia for two reasons. First, whether or not one thinks this is right and proper, the arrangements for the reburial of Richard III don’t, at present, seem likely to be in the hands of the Royal Household. (Personally I don’t think this is correct procedure.) Second, every crown in the Royal Regalia today dates from a period long after the reign of Richard III.
It was for these two reasons that I suggested, after his remains had been found, that a special funeral crown should be made for Richard III’s reburial. The idea first came to me in September 2012, while I was carrying the box containing his bones from the Greyfriars site to the vehicle which was to take the bones away for scientific examination. And I offered to pay for the crown myself, because, having carried him, I can’t help feeling close to Richard III.