Why does ring size not affect the price of an engagement ring?

Keeping things simple, and in concise with your question, the pricing of larger finger sizes is not something that many online retailers will account for. They will build in a standard price for a ring mount in the chosen metal for each diamond size. This can even be the same across different ring designs, which simplifies the pricing process. The variation of weight with finger size of any mount will be fairly negligible and only much larger finger sizes will carry a noticeable weight difference. At Serendipity Diamonds, we price the ring mount within the calculation according to the weight of the exact ring mount design, setting size with a premium only for the larger sizes (Q+) where a noticeable weight difference will be found.

It does, but in the case of the mentioned Blue Nile and any other mainstream / high-street jeweller who sells diamonds in off-the-shelf semi-mount  settings, the difference in the metal weight is so small and re-sizing  or using the correct mount size is so simple, that it is just easier for  the vendor not to maintain price lists for the size matrix. Remember,  in case of an engagement ring, the customer is buying a diamond with  retail premium set in a standard mount setting, which costs a fraction  of the diamond. There is no design, craft or expertise involved in the  process. The simpler - the better. So, yes, size doesn't really matter  for all these commercial, standard jewellery pieces with diamonds.  However, it does matter for more complex rings - like eternity rings,  which is impossible to re-size, or designer pieces where the size will  require to cast a new mold.

Custom jewelers will price their goods to size.  Mass production jewelers most likely average the prices across the most common sizes and either charge more for sizes larger than their norm or less for those smaller than their norm.  I know at least two manufacturers that our store deals with that does this for engagement rings and wedding bands.

Ring size usually makes no difference when it comes to the prices of engagement rings, since the metal portion accounts for only a small part of the overall cost. Mass produced rings have their prices averaged, while some custom jewelers will price smaller sizes just a little below average and larger ones just a bit above. Here at https://www.worthy.com/, ring size doesn’t affect the price of an engagement ring at all, since all rings are sold at auction and the market alone determines the cost.So, what really determine the price of an engagement ring? There are a few factors. First of all, the center diamond or gemstone is a huge factor. Side stones are also a consideration; the better quality they are, the more the ring is likely to cost. Sometimes brand name makes a difference, and of course the type of precious metal that’s used in crafting the ring’s setting and band also impacts price. Finally, much of the cost associated with an engagement ring comes from retail overhead. It’s very expensive to maintain a storefront and provide employees with fair compensation, so part of the money you pay for a retail engagement ring goes into costs like these.