What does it mean that the customized ring is engraved with both Au750 and DQ950?

The customized ring is engraved with both Au750 and DQ950, which refers to the reserved material of the diamond ring.

Au750 is an alloy containing 75% gold, which is known as 18K gold. Some people may ask whether 75% gold content is bad. Actually, it's not. Au750 has its reasons. Because gold is soft, jewelry made of it is easy to wear and deform, so gold with high purity will not be used as a diamond ring to avoid diamonds falling off. While 18K gold contains 25% other metals, which has high hardness and good ductility and can be used as a diamond ring stopper.

Pt950 refers to jewelry containing 95% platinum and the remaining 5% other precious metals, with the imprint of Pt950.