Methods of preparing highly purified steviol glycosides, particularly steviolmonoside, steviolmonoside A, steviolbioside, steviolbioside A, steviolbioside B, rubusoside, stevioside, stevioside A (rebaudioside KA), stevioside B, stevioside C, rebaudioside E, rebaudioside E2, rebaudioside E3, and rebaudioside AM are described. The methods include utilizing enzyme preparations and recombinant microorganisms for converting various staring compositions to target steviol glycosides. The highly purified rebaudiosides are useful as non-caloric sweetener, flavor enhancer, sweetness enhancer, and foaming suppressor in edible and chewable compositions such as any beverages, confectioneries, bakery products, cookies, and chewing gums.