Carbon trade in both types of diamonds exists, the two markets act in dramatically different ways. Unlike precious metals such as gold or platinum, gem diamonds do not trade as a commodity: there is a substantial mark-up in the sale of diamonds, and there is not a very active market for resale of diamonds. Industrial diamonds are valued mostly for their hardness and heat conductivity, with the gemological qualities of clarity and color being mostly irrelevant. About 80% of mined diamonds (equal to about 100 million carats or 20 tonnes annually) are unsuitable for use as gemstones are relegated for industrial
Commodity (Marxism) of value, product-values in an open market are regulated by the average socially necessary labour time required to produce them, and price relativities of products are ultimately governed by the law of value. Commodity-trade, Marx argues, historically begins at the boundaries of separate economic communities based otherwise on a "non-commercial" form of production. Thus, producers trade in those goods of which those producers, have episodic or permanent surpluses to their own requirements, and they aim to obtain different goods with an equal value in return. Marx refers to this as "simple exchange" which implies what Frederick Engels calls "simple commodity