Chintamani is not a jewel, nor Kalpavriksha, a tree nor Kamadhenu, a cow. They are all names for the fruits of Tapas. They are powers that automatically accrue to a person as a result of Tapas. He realises all that he wishes for. It is called Kalpavriksha-siddhi. When he subdues all desire it is called Kamadhenu-siddhi.
Chintamani-siddhi is the stage when you have no chinta or worry or mental agitation; a stage when all sorrow is kept afar. When chinta ends and the supreme ananda is won, it is Chintamani-siddhi. Chinta must disappear from thought, word and deed. (Prema Vahini, p. 53)