When choosing diamond stud earrings, consider the size, quality, and shape of the diamonds, along with the style and color of the settings. Diamond studs don’t need to be huge to be beautiful. Aim for a half carat total weight (0.50 CTW) or more: the individual stones would be at least 1/4 carat (0.25ct) each. If you plan to wear your studs regularly or if you want to pair them with cocktail wear, consider investing in a slightly larger size: 2/3 CTW (0.33ct each) or more would be ideal.
Shape & Cut: Round brilliant diamonds have the most sparkle of any diamond shape, especially when set in basket mountings that allows more light to catch the stones. Princess cut diamonds are an excellent alternative to round, if you are looking for something a little different. For example, princess-cut diamonds set in rose gold would be a singular combination. Any symmetrical shape would work well. It may be better to avoid marquise or pear-shaped diamonds: if one earring spins sideways, for example, it creates an asymmetrical look.
The cut of the diamond determines its brilliance and should be as high a grade as possible. Choose a cut of at least “Very Good” for maximum sparkle. A diamond with a "Good" cut reflects most of the light that enters it, and is an excellent value.
Clarity: The diamonds' clarity doesn’t need to be flawless, but should be high enough to exclude any inclusions that are visible to the naked eye. Earrings sit near eye level, and any obvious inclusions in the stones can be easily observed. Choose at least grades SI1, SI2 or better. “SI” means “Slight Inclusions” that are visible under 10X magnification.
Color: When choosing a color grade for diamond earrings, the upper range of the near colorless tier (either G or H color) is an excellent compromise between cost and quality. Anything much lower (J, for example) may exhibit visible yellow undertones in bright sunlight.
Earring settings can be clean and classic or detailed and romantic. Choosing a setting style is a matter of personal preference. Consider whether you want your studs to sit high or low on your ears. A higher setting can add desirable heft to smaller stones. A lower setting may feel more comfortable and secure.