The cost price of diamond products of famous brands such as Chow Tai Fook and Zhou Shengsheng is about one 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. As long as they give you a 20% discount in Chinese mainland, that's fine. Nothing is worth it.
Besides, you can get a 20% discount on such an expensive ring. Come on, you need help to get the price.