Good to find gold. Several companies have registered ‘DIAMOND LOVE’ as a trademark for jewellery. As is sometimes the case, a trademark can be re-registered anew if the original registrant has allowed it to lapse.
It’s a cancelled trademark for the Hearts on Fire Company of Massachusetts (registered in 2000 and cancelled in 2022) but as far as I can see, they made rings set with diamonds and precious stones but didn’t make plain wedding bands.
It’s an abandoned trademark for Mopaz Diamonds, Inc. of New York, but was only registered for loose diamonds and diamond jewellery.
It’s a live trademark for GemsOne Trading of New York for jewellery and imitation jewellery, but they registered it as a mixture of upper and lower case letters: ‘Perfect Love’. They’ve been in business since 1974 but it looks like they only registered the mark recently and seemingly only use it on precious gem and diamond jewellery.
My guess is it’s the mark formerly owned by the Jewel Box Stores Corporation of North Carolina. They registered it in 1966 for diamond rings and wedding bands and it expired in 1987 after they failed to renew it.