Quality of gold is measured in carats. 24 carat gold is considered to be pure gold and usually this is available in the shape of biscuits. These biscuits have a seal on it and come in various weights. Pure gold is very soft and usually not suitable for making jewelry as designs cannot be made and then they will break easily. To make the gold hard so that jewelry can be made out of it, some alloy is added. As such you may find jewelry of 22 carat gold, 21 carat gold, and 18 carat gold in the market. The more the alloy added the lesser the gold content and the stronger will be the jewelry. While buying gold jewelry, you can ask the shopkeeper about the carat and he will tell you. Also, at some place in the jewelry the carat is also embossed and if you look carefully you will find it in fine print. I do not think there is any difference in quality of gold between shops. As for your questions regarding the quality of gold between the Gulf and India, I cannot say much. However, whenever I have sold jewelry in my home country which I bought from here, the gold shop dealers immediately recognized the jewelry was from overseas and locally made, This may possibly be from the designs and craftsmanship. Trust this give you some information from the little knowledge I have in this field.