I am a sucker for lockets, though I never put photos or mementos in mine. This would be perfect for an Irish friend, or someone who just believes in the four leaf clover/shamrock as a bringer of luck. It has an enamel monogram on the reverse, which looks like the letters BA to me, though seller Dover Jewelry seems to have misidentified this as a botanical theme.
This is 18k yellow gold with green and red enamel. It weighs 23.1 grams and measures 40 mm long (including bail) and 26 mm wide.
It sells for USD$1,750.