The numbers on rings are super tiny so what you are probably reading is either 42.5 or 92.5. If the ring is gold you are seeing 42.5 which means that the ring is 42.5% gold and the rest alloy. If the...
Japan
It is the purity of that metal. which means if you melt your metal you get 72.5% pure of that metal. Just like 916 for gold and 925 for silver.
DQ stands for Diamonique, which is the TV shopping channel QVC's brand of cubic zirconia (simulated diamonds).
genuine