The collection value of lab-grown diamonds is not entirely related to their size (ie, carat), but mainly depends on factors such as their quality, color, purity and cut. Therefore, even small-sized lab-grown diamonds can be highly collectible as long as they are of high quality and have good characteristics.
Typically, however, larger-sized lab-grown diamonds tend to be more sought after by collectors, as they are more aesthetically stunning and relatively rare. In general, lab-grown diamonds with a carat weight over 1 carat are considered larger diamonds.
It should be noted that the collectible value of lab-grown diamonds is affected by market demand and supply. Even high-quality large-sized lab-grown diamonds may not be highly collectible if there is insufficient market demand. Therefore, when considering the purchase and collection of lab-grown diamonds, in addition to their size, many other factors need to be considered to ensure their true collection value.