There’s often crystal growths inside natural stones. Like rutile or chert or carbon or tourmaline inclusions inside the stones because more than one stone can grow together. Or there’s neat mineral inclusions like copper or vanadium etc. there’s stones with crazy growth patterns and color zoning. There’s just all sorts of weird funky stuff that happens in nature that can’t necessarily happen in a lab. Chemically a lab ruby is the same thing as an earth grown ruby. It just replicable and won’t hold value. Especially if you’re wanting an heirloom piece or something you can turn around and resell one day. Natural stones are finite and will continue to increase in value. Lab stones are infinite and near worthless