shehasit

Because diamonds are not priced only by carat weight but also clarity, cut, color, fluorescence, brilliance, etc.

At chain stores, most of their diamonds are purchased by mass and very roughly eye-graded in bulk. They have central suppliers for all of their stores. For example, Zales will have a group of diamond buyers that supply all of their stores with diamonds and the stores get what they get.

The diamonds are then priced based very routinely on what is called the "Rappaport" guidelines (aka the "Rapp sheet"). It's a NY-based company whose pricing is sort of the industry standard.

Generally a diamond buyer wants to get his diamonds 40-50% "back of Rapp" (40-50% less than the stated wholesale value listed on the Rapp report). So independent jewelers, at least ones that do enough volume where they can buy enough diamonds to get good discounts, will pick through a diamond parcel, individually grade each one, cherry-pick the best ones and get the cheap parcel price on the parcel of diamonds while actually only paying for the best looking diamonds.

Some jewelers are better at this than others. Some have priority pricing over others. Some work on smaller margins on their diamonds (the typical markup on a diamond is 3-3.5X). This is the reason for the pricing difference. You will see price variation in how much a retailer sells a Samsung TV. Just imagine how much more variation there will be when you're selling something when its value is placed entirely on a subjective scale such as "beauty"!

Generally, a jeweler will not (or can't) drop below 2x cost. That's considered their "key" - or the point at which they're not making enough money to survive.

So rather than being the asshole that comes in and tries to absurdly lowball someone without any knowledge, your best shot is this:

Go to an Independent jeweler (non-chain store) that buys his/her own diamonds. Bring cash. See if you can talk to the owner or the manager. Make sure the diamond passes your eye/loupe test. Make sure it's not clarity-enhanced. Look at the retail price and offer 30-40% less than that in cash (unless it's a store that has "no discounting" - in which case you can offer maybe 10% less for a cash deal).

You have the peace of mind of buying from a reputable jeweler, saved a shit ton of cash and have a place that will clean and inspect your jewelry for free. Happy shopping.

A lot of vendors, especially stateside vendors, have switched to suppliers that claim to be conflict free. It's pretty difficult to be certain but they do make an effort. The vast majority of the U.S.-based bridal manufacturers have changed to conflict-free suppliers.