I was watching world strongest man competition 2018, and there was this "Bullion toss" contest
Those huge men were throwing/tossing 20 kg to 30kg Gold bars 15 feet high. They were solid gold bars or iron bars plated with Gold ??
Natural gold/Pure Gold are slightly reddish yellow in color. Colored gold in various colors can be produced. Mostly, ranges from the colors reddish, white-ish, and greenish. This mean that this colored gold are not 'pure gold'. It might be plated or composite material. Composite means a mixture of two or more material to form another material. Gold can be mixed with alloys and intermetallic compounds. Color be change thru surface treatment.
Pure Gold can be classified as 24Karat by definition. Thus, colored gold are less pure 18K (75%), 14K (58.5%), 10K (41.6%), or 9K (37.5%).
Colored golds can be classified in three groups;
1. Alloys with silver and copper in various proportions, producing white, yellow, green and red golds. These are typically malleable alloys.
2. Intermetallic compounds, producing blue and purple golds, as well as other colors. These are typically brittle, but can be used as gems and inlays.
3. Surface treatments, such as oxide layers.