Synthetic Diamonds are one of those odd things that no one really seems to know much about, or talk about. Did you know that they are nearly identical to real diamonds to the untrained eye? Lab-grown or man-made diamonds [synthetics] have the same chemical and physical properties as natural diamonds. A VERY interesting fact, right? Here are a few more: Although synthetics are not formed naturally, they have the same chemical composition and physical properties as natural diamonds. Synthetic diamonds are grown in days or weeks depending upon size, whereas natural diamonds were formed millions of years ago under enormous heat and pressure at depths of around 100 miles below the earth’s surface.