PROS
In diamond engagement rings, as in everything else, the selection and variety you must choose from when shopping online are simply unbeatable by any physical merchant. Unlike brick-and-mortar stores that are limited by many considerations, including space, security, and costs, online merchants do not have to worry about those things and can offer a virtually unlimited array of jewelry for you to choose from. Talking about costs, brick-and-mortar stores usually have quite a lot of overhead costs due to the many furnishings and facilities required in a jewelry store, think rent, special light fixtures, etc. Online stores must only operate and maintain their website and logistics base. That reduces their cost of doing business drastically, meaning they can pass on the savings to you by offering better diamonds for reduced prices. In a brick-and-mortar store, the overhead is passed on to you, the buyer, meaning increased costs of the goods.
Online stores also usually have solid return policies, effectively giving you a period within which you can decide not to continue with that ring. Go through the return policy carefully to ensure you will get your money back, not an exchange, and not after bogus amounts have been deducted as “restocking fees.”
CONS
The nature of the internet itself is the first, most obvious flaw in buying diamonds online. An unregulated market will have its share of unscrupulous merchants who are just out to swindle unsuspecting buyers.
Your inability, as a buyer, to physically assess the stone before you buy it is another flaw, as it robs you of the opportunity to make the in-depth evaluation that only handling the diamonds can enable. Conversely, most people, including you, cannot evaluate a diamond properly. The advantage conferred by physical assessment may not be so big, and pictures may suffice for most people.