THE recent sale of two Cartier ''mystery clocks'' to local Chinese buyers - for a total of $24 million - may have provided the impetus for the firm to bring a special Cartier collection to Hongkong. Starting on Wednesday at the Cartier boutique in Pacific Place, the ''Made by Cartier'' exhibition will coincide with the launch of a book of the same name which tells the story of the company and the pieces - many now collectibles - it has created. The exhibition, which will be accompanied by another exhibition and sale of contemporary jewellery watches, will be on for eight days. ''We are concentrating on pieces from the art deco period for the antique collection,'' said Cartier Hongkong's Mrs Corinne Garnier-Djaoui. Two antique experts from the company spend most of their time travelling around the world visiting antique dealers and clients to buy back Cartier pieces. ''We now have about 500 pieces in our collection, a small section of which will be on show in Hongkong. ''We like to buy these pieces back because we feel there is something historical and important in them,'' said Mrs Garnier-Djaoui. The jewellery watches were shown recently in Geneva, and will be bought to Hongkong for potential buyers. One hundred pieces, valued at $15 million, will be up for sale. ''There are some very important collectors in Hongkong, so this is quite a market for us,'' said Mrs Garnier-Djaoui.