That sounds a lot like the Christmas decorations box... I've just emptied that box and the whole cupboard and can't find them! (Now have to round up all the hats DS has been playing with!)

If it helps, the engagement ring is the yellow gold, three diamond twist ring and the eternity ring is a white gold dress ring with six diamonds arranged as two threes in a leafy sort of design. (DH picked them both without me, don't tell me that two different coloured golds looks odd together!)