Is hexyl acetate natural or synthetic?
Because you can design a synthetic polymer to exactly meet your needs. You can modify a natural polymer sometimes if it's not what you need, but at that point is it really a "natural" polymer? Take cellulose--a perfectly serviceable natural polymer, they build millions of homes every year out of it. But what if you need a polymer you can see through? Cellulose won't work for you there unless you dissolve it in acetic acid…
HPHT (high-pressure high-temperature) diamond or CVD (chemical vapour deposition) diamond are the process to make synthetic diamond. However, all properties are the same as natural diamond (hardness, light reflection, thermal conductivity etc) but it is extremely difficult to make large carat size quality stones such as natural diamond 2 Ct and above.