NOW is the time to invest in gold coins, according to coin dealers. They have tipped gold prices to bottom out and demand for existing collections to surge as a result of recent moves to abandon the Queen's figure in future coin and note issues. The Government had stopped issuing gold coins since 1987 but it is expected that future issues will adopt the new de-colonised designs. Mr Anthony Lee Hon-man at coin dealers New Century Collections said the risk of gold prices falling was limited after the sharp fall since mid-1980s. He added change in designs would make existing issues rare commodities. But he warned key distinction must be made between coins and medals in view of big disparity in values. Gold coins are much more valuable because they were government issues and are, therefore, legal tender. ''They command a basic worth which is at a premium above their face value,'' said Mr Lee. ''This secures their capital value.'' But this rule does not apply to gold medals which are private issues. While circulation of gold coins are predefined, supply of medals is at the discretion of private issuers. Price of medals will go down with increased supply. The most prominent local collection is the 12 gold coins issued by the Government since 1976. They depicted the 12 animals featured in the Chinese calendar but their prices have seen a sharp fall in recent years. Sharp fall in gold prices since the mid-1980s were held partly responsible for the decline. The surge in collectors seeking to sell their holdings since 1989 had also dampened prices. Mr Ma Tak-wo of coin dealer Tai Sei Stamps and Coins (Hongkong) Ltd believed the increased supply was linked to the surge in emigration after the Tiananmen crackdown in June 1989. Gold coins to mark Queen Elizabeth's two visits to Hongkong are also prime collection items. Un-circulated edition of the set of 14 coins worth about $27,000 at present compared to $40,000 seven years ago. The proof set was traded at about $55,000 now against $80,000 in 1985.