Synthetic spinel has been commonly used as a substitute for many natural gemstones. The "crosshatch effect" show in polariscope indicates the gemstone is an ADR reaction in flame-fusion synthetics. Further testing such as, showing strong red, orange-pink or pink under CCF and chalky blue under shortwave UV light will helps to determine whether or not it’s a natural or synthetic spinel. ••• www.wgi-global.com ••• #wgilabsuk #wgistudio #gemologist #hattongarden #14grevillestreet #london #uk #insta