Make sure, if possible, you go to a reputable jewellery store with professionally educated gemologist to purchase any diamond jewellery. They can act as your guide as you look at natural and man-made diamonds.
A sales associate should articulate or represent and disclose accurately what they are presenting to you. If they are calling it 'diamond,' you are assuming it is natural. If it's not natural they need to be forthcoming in their description and are required by the Federal Trade Commission (FTC) to call it laboratory-created, synthetic, laboratory-grown or manufacturer-created.
Ask the sales associate if it is a natural or man-made diamond and how they know this information.
Synthetic diamonds may be difficult to recognize by a jeweller or a trained gemologist, but they do not present an identification challenge for GIA. There are a variety of instruments being offered to jewellers so they can check for synthetic diamonds, but GIA does not use them so it is not appropriate for us to comment on their operation or accuracy.
Ask for a diamond grading report from a recognized gemological laboratory, these clearly disclose the identity of the diamond. GIA reports for natural and synthetic diamonds look very different.
When you're making an investment in something as precious as this, you should ask for a grading report.
It is important to note the major distinction between lab-created diamonds and diamond simulants. Diamond simulants, such as cubic zirconia and moissanite, look similar to diamonds but are not true carbon crystals. Simulants do not have the same chemical and physical properties as natural diamonds and therefore sell at much lower prices than lab-created diamonds. Simulants can be distinguished from natural or lab-created diamonds using only the naked eye.
Natural and lab-created diamonds have thermal conductivity properties that differentiate them from cubic zirconia with a handheld diamond tester. Some lab-created diamonds, along with some natural colored diamonds, may be mistakenly identified as moissanites when using certain diamond testers due to similarity in their electrical conductivity. However, gemologists can typically distinguish between diamond and moissanite due to their differing refractive properties, with moissanites being double refractive and diamonds being single refractive.