While a slide in the price of gold on Tuesday triggered investors' concerns, an expert said a gold price rally is a "marathon" for 2020 and encouraged investors to own the precious metal as part of a diversified, long-term investment portfolio.

The price of gold is still in an early stage of a cycle, Wang Lixin, managing director of the World Gold Council in China, said on Tuesday at a discussion meeting of its recently released document regarding gold investment principles for investment products providers and guidance for investors.

The price of gold tumbled 4.7 percent to $1,932.28 on Tuesday after a multi-week rally and crossed $2,000 per ounce to a record high.

WGC's release of gold investment guidance also offered different suggestions to investors with various demands.

Its gold investment principles for investment products providers called for high-level fairness, transparency and honesty to bolster a good market environment after consulting industry experts from over 15 countries.