The cost price of diamond products of famous brands such as Chow Tai Fook and Zhou Shengsheng is about a quarter to a third of the marked price, and the rest is gross profit. If you can get the first-hand source of diamonds in South Africa, or directly buy loose diamonds for processing, or directly dig out a diamond, it is definitely not cost-effective.
However, if you believe in the value of brands, but you don't know about diamonds, and you think it is more risky to buy rough stones, and the products processed are not as good as those processed by these big brands, then it is definitely cost-effective.
In short, it is definitely the seller who buys the diamond ring, no matter the big brand or the small brand. Maybe the diamond market will rise within a few years after consumers buy it, but it may not rise too much, so it is just for wearing. As long as you like it and have the ability, you won't lose money if you buy it. As for wearing it for several years, it is difficult to sell it at the original price or add value.
Besides, white diamonds below 1 carat are not very collectible. Just put it on, don't think too much. Zhou Shengsheng, Chow Tai Fook and other big brands go to Hong Kong to buy, which is the most favorable. In Chinese mainland, as long as they give you a discount of about 20%, it's fine. The key is that as long as you like this style, there is nothing to lose by wearing it.
For your diamond ring, only the color is better, and everything else is just so-so. Not compared with loose diamonds and other big or small brands. As for Chow Tai Fook, you have to sacrifice some color or clarity and choose a diamond ring close to 1 carat. If it is 1 carat, it will be much more expensive, even if you choose a diamond ring of 0.99 carat. Because of the color and clarity of diamonds, it is difficult for the naked eye to distinguish, but the price will be much worse. Although buying ordinary diamonds mainly depends on personal preference, the size, clarity and color should be considered first. Personal opinion, for reference only.