It's important to understand the difference between lab-grown diamonds and diamond look-alikes (called simulants). Lab-grown diamonds are made from carbon, just like natural diamonds. Simulants, like moissanite and cubic zirconia, may look like diamonds but aren't made from real carbon crystals.

Two of the most common diamond simulants are moissanite and cubic zirconia.

• When picking a diamond, knowing what your partner likes will help you decide which of the 4 C's (cut, color, clarity, and carat) matter most. Usually, sparkle (which comes from the cut) and color are the top priorities, while diamond size might not be as important. The shape, depth, and symmetry of a diamond can also affect how big it looks. Longer shapes, like oval and emerald, tend to look bigger than round diamonds because they hold more of their weight in their length and depth.
• If you're looking to save on the engagement ring band, consider white gold instead of platinum. Platinum is the priciest metal, while white gold still has a shiny, cool-toned finish. Plus, white gold doesn’t rust, tarnish, or corrode and is great for detailed designs.

So cubic zirconia and moissanite aren’t diamonds of any kind, though they can look very similar..

Cubic zirconia and moissanite are not real diamonds, but they can look very similar. Since they don’t have the same chemical or physical properties as real or lab-grown diamonds, they're much cheaper. You can usually tell them apart from real diamonds just by looking.

Real and lab-grown diamonds conduct heat differently than cubic zirconia, so a handheld diamond tester can tell the difference. However, some lab-grown and natural colored diamonds can be mistaken for moissanite because they conduct electricity in a similar way. But gemologists (experts in gems) can tell them apart based on how they bend light. Moissanite bends light in two directions (double refractive), while diamonds bend it in only one direction (single refractive).