Use an open flame, such as firewood, to identify the authenticity of gold jewelry.

Fire identification of the authenticity of gold jewelry is "seven green, eight yellow and nine red, four six are not gold." Look at the color of the jewelry after the fire:

Seven green means that 70% (including 70% gold) is blue-yellow in color. Eight yellows means that 80% (including 80% gold) of gold is yellow. Nine red stripes mean that 90% and more than 95% of gold is deep red yellow, and 90-95% of gold is light red yellow. 46% of gold does not appear, indicating that the purity of gold is less than 60% (including 60%), and the color presented is no longer the color of gold. Gold below 60% is yellow and white, and gold below 40% is all white.

Methods for identifying the authenticity and purity of platinum and platinum;

(1) visual inspection method: marking: each piece of jewelry should be engraved with the chemical composition seal, such as (pt 900) and (PT 750). All stamps that begin with "PT" are platinum ornaments: platinum is tin white, that is, white with gray and bright luster.

(2) Instrument detection: Hardness test: the hardness of platinum is 4-4.5 degrees, which is harder than gold and silver. It is scratched with a knife or glass, but it will not be scratched by nails. Density measurement: Platinum is extremely dense and feels heavy when weighed by hand. The density measured by hydrostatic pressure method should be 2 1.43g/cm. The melting point of platinum is as high as 178. Acid test when the color is unchanged: platinum is chemically stable and insoluble in ordinary acids. Scrape the platinum on the touchstone, drop hydrochloric acid, and try with hydrogen peroxide under the condition that the wear marks are unchanged: take a little platinum powder and put it into the hydrogen peroxide bottle, and hydrogen peroxide will immediately produce bubbles. After the reaction, platinum can still be used without any damage.