G750 is 75% gold, which means that the ring material is 18K gold.

12.5 should be the diameter and size of the ring.

The weight of this ring is estimated to be less than 2 grams, not pure gold. Besides, I didn't see anything embedded in the picture.

Even if it is pure gold 200 yuan/gram, the cost of this ring is around 200 yuan, and the brand is unknown. It's estimated that it's only a few hundred dollars if you buy it.