The Five Elements scheme — wu xing — sorts colours, seasons, directions and much else into wood, fire, earth, metal and water. A traditional reading takes a birth date and works out which elements are strong and which are thin, then suggests colours and materials to fill the gap.
We apply that method to stone selection and send the reasoning on a card. What we do not do is make any claim about what the result will change — this is a decorative, personalised object built on a specific cultural method, and the card says exactly what was done and why. Ordering takes a birth date, nothing else.