G750 is made of 18K gold, containing 75% gold. JLF should be the product series number.
Diamonds are not big, but 1 1 minute diamonds (you didn't mention other parameters) are generally 500-600.
You didn't say the weight of the ring, so it's difficult to estimate the price of gold. Now 18K is around 180 yuan per gram, plus 100 yuan.
Diamond+gold can almost get the cost of the ring. Multiply this price by 1.5-3.5 to get the selling price of the mall. Of course, if it is a big brand, it will be higher.