It refers to the unit of weight of a diamond. Since a diamond becomes rarer as its weight increases, the larger the diamond, the more expensive and valuable it is.

Just as the number of carats determines the value of a diamond.

This feature of the Diamond Card gives added value to card members' shopping experience via an expanded Diamond Rewards Program that lets them earn one (1) rewards point for every P50 charged to their card or P125 from supermarkets, drugstores, or gas stations.

See Rewards Points Redemption Table here.