For example, South Red Agate: When some consumers buy South Red Agate, they will find some black parts on it. This black south red agate is not a real south red agate. It is the associated stone of south red agate, and its value is very low. Many unscrupulous merchants trick consumers into saying that black southern red agate is the best and the selling price is very high. In fact, the value of this black associated stone is not high and the sales volume is also very low.