Crypto-currency, especially decentralized, stable can not be by nature. After all, its price is formed solely on the basis of the ratio of supply and demand, and they are always volatile, because they depend on the conflicting decisions of each of the millions of participants in the crypto-currency market. Only a coin of USDT, which in general is always equal to one dollar, can be considered stable. However, this is not a full-fledged crypto currency, because it is actually a digital copy of the dollar.