Market uncertainties have not affected the value of rare and high-quality gems, with many collectors continuously looking for exceptional stones to further enrich their treasure troves. Among these investment gems, an alluring variety of chalcedony called Gem Silica – also traded as Taiwan sapphires – has become more popular especially among Chinese buyers over the years.

According to Yu Chung-ta of high-end gem dealer Chia Ta Jewellery Co Ltd, these so-called Taiwan sapphires have always been favoured by Chinese collectors who are partial to materials with an icy appearance that resemble top-quality jadeite. "With trendy and fashionable designs, we see tremendous growth potential in this product category among younger consumer groups," noted Yu.

Taiwan-based gem trader Shining Shining said these gems have a relatively richer quartz content and a hardness of 6.5 to 7 in the Mohs scale. Colours range from blue to bluish-green and green. Gem-quality greenish-blue chalcedony can be mined in Chile, Indonesia, Peru, Taiwan and the US. These translucent-to-opaque gemstones are often polished into cabochons and set with oriental designs, which suit the tastes of many high-end jewellery collectors from Asia. These gems also come with a wide price range depending on their quality, according to the dealer.