how to tell the quality in semi-precious gemstone jewelry? 

Because the video is said while thinking, there is a little confusion. The 4C is evaluated from the cut gemstone. Therefore, the round bead of our semi-gemstone is evaluated from the color, the degree of cleanliness, the roundness of the bead and the size of the bead. There is no specific value to measure, it is mainly comparison.
Currency of price in video is PH peso.