This is definitely the most affordable and convenient place to buy a diamond ring. Before buying, make sure that the seller is authentic as well as check if they give a lifetime warranty and low price guarantee on the purchase. You can also use the online chat feature to ask the seller anything related to the diamond rings you prefer.
Wholesalers make profit by selling bulk amount of goods; hence, the prices per loose diamond are lower than what you could get from a retailer. Still, the pricing is quite similar to that of online sellers. Note that wholesalers usually sell only to the customers who can buy in large quantities and they will give a better deal for it.
At retail stores, you can get a wide variety of diamond rings, which you can try on. You can even ask the seller to show the stone certification, as it is important to protect the investment value of the stone. However, the prices in retail stores are around 30-50% higher than the wholesale or online prices.