No — lab-grown (synthetic) diamonds fall under heading 7104, not heading 7102, which is reserved for natural diamonds. Within 7104, synthetic diamonds are further split between unworked or roughly shaped (710421) and worked but not mounted (710491). This distinction matters because the duty rates and trade-remedy exposure can differ from those on natural diamonds.

Piezo-electric quartz is classified separately because its primary commercial use is as an electronic component — in oscillators, sensors, and frequency-control devices — rather than as a gemstone. Other synthetic stones in the heading are valued for their gem or abrasive properties. If a quartz crystal is intended for electronic use, 710410 is the correct subheading regardless of its visual resemblance to a gemstone.