Abstract: User-defined gemstone-based products include one or more gemstone(s) that are selected from a database of gemstone categories based on a user's birthday. Preferably at least one of the gemstone categories corresponds to a Zodiac sign and/or at least one of the gemstone categories corresponds to a month of a Gregorian calendar. In the preferred embodiment, the database of gemstone categories includes Modern birthstones, Ancient birthstones, Mystical gemstones, Zodiac gemstones, and Talismanic gemstones. Based on the birth date and Zodiac sign of the user, one or more gemstones corresponding to the user-defined gemstone categories are determined. The gemstone categories are presented to a user for selection of one or more of the gemstone categories. These gemstones and user-defined Zodiac symbol are then arranged on a user-selected piece of jewelry.