This is a 9ct Yellow Gold Oval Acorn Engraved Centre with a Beaded Edging Front Locket.
The top of the Acorn is Rhodium Plated. 
The inscription on the back of the locket reads “ FROM LITTLE ACORNS MIGHTY OAK TREES GROW”
Weight: approx 1.74g
Length: approx 2.7cm
SAFE1.