IT probably wasn't the most diplomatic of questions to put to bubbling Flora Cheong-Leen when I met her yesterday with jeweller Kai-Yin Lo but I just couldn't resist it. ''How come you are not wearing any of Kai-Yin's creations?'' I inquired. The question wasn't entirely inappropriate since the press conference we were attending was being held by the internationally known jeweller to announce the Kai-Yin Lo Jewellery Design Competition at which Flora will be one of the judges. A few moments later Flora and Kai-Yin were putting the matter right, for I spotted them huddled by the display of jewellery while Flora chose a pair of semi-precious ear-rings and put them on. This is the second successive year that Kai-Yin is staging this competition, which she calls ''a resume of 10 years' development of my company''. She adds: ''I have been an ambassador for semi-precious stones, especially in the United States where my name is synonymous with this type of jewellery. ''But I can recognise the difficult, often lonely path, that new artists have to travel. ''So I hope by holding this competition we can get young designers interested in this particular segment of the jewellery market. Kai-Yin, who likes to refer to her Hongkong clients as ''society freshmen and working women like me who are rushing around'', can roll off an impressive list of well-known figures who wear her personally designed pieces. Imelda Marcos, the former first lady of the Philippines, for one, ''who used to give away my stuff'', says Kai-Yin sounding a tone miffed. Other dedicated customers of Hongkong's very own jeweller vary from Dame Lydia Dunn - ''who prefers travelling and TV jewellery'' to Evelyn Lauder (of the perfume family), Ann Getty (wife of oil billionaire Gordon) and actress Linda Evans. And what does Kai-Yin herself wear? ''Mostly my own, but that's because semi-precious stones represent so many colours suiting the needs and moods of the day. ''I don't go that much for designer jewellery. The days when I had to wear designer things to instil confidence in myself are long gone.''