India is one of the three largest cutting and trading centers in the world (the other two are Tel Aviv, Israel, and Antwerp, Belgium). Other major markets include Dubai, Shanghai, Hong Kong, London, Los Angeles, New York, and others. So, if you're in one of those centers, have access to a true wholesaler, and (most importantly) have the ability to abide by the terms of wholesale (buying large quantities of stones, committing to regular repeat purchases, understanding that there are no returns, trade-ins, exchanges, or after purchase support of any kind, etc.) then you can save some money. This is the nature of the wholesale business in ANY industry. You can get a volume discount, but you have to buy in volume! And in diamonds, that discount isn't as significant as it is in many other industries (clothing springs to mind as one with MASSIVE markups).
In the diamond space, the largest markup occurs at retail. For example, I have a client who owns a large fancy jewelry store in Florida. He tells me that every diamond I sell him gets marked up 65% (this is many times my margin!). Why? Because he has to pay his diamond supplier, his sapphire supplier, his pearl supplier, his gold supplier... And Rolex, and gold, and silver, etc etc... But beyond that, he has a staff of more than 30 people, a 6,000sqft store, insurance, utilities, and more. And let's not forget the $10,000 he spends EVERY DAY on marketing. Online ads, TV, radio, billboards, bus sides, you name it. He has bills that I don't dream of in my worst nightmare. So of course he has to mark up the diamonds! Otherwise he can't keep the lights on.
So, if you want to avoid retail markups, don't shop retail! Find a good, honest, reputable dealer and work privately. You'll get much more bang for your buck. You'll also often get better expert advice. For example, my business specializes in diamonds and diamond jewelry. If you come into my office and ask to see my selection of pearls, or watches, or rubies, I have nothing to show you. My expertise and inventory are invested in diamonds. Retailers, by their nature, have to be generalists. They have no idea who is going to walk in the door tomorrow or what they'll be looking for. I, on the other hand, am a specialist.
As an analogy, if you don't feel well and don't know what's wrong, you probably want to see your family doctor. That's your local jeweler. But if you know you need open heart surgery, you want a cardiothoracic surgeon. That's me. If your knee hurts, or you have the sniffles, I'm not your guy. But if you need your ticker tinkered with, give me a call.
I hope that helps!