here is 2 types of Okinawa coral calcium, that is above sea coral and below sea coral. True Blue is high grade, above sea coral calcium, that also contains 73 other trace minerals and elements, along with the highest level of vitamin d, vitamin d3.  True Blue Coral Calcium is made up of the purest of coral calcium, from fossilized coral reef heads, a more costly coral to work with, but in the long run working with this coral calcium is much better and beneficial for your health.