Well,honestly I haven't heard that for good luck, one should put his/her martenitsa under a stone.I've heard the "tree" story and also I hope that you've been told about the stork and swallow.Basically you should take off your martenitsa in two occasions:1.You saw a stork or a swallow and then put the martenitsa over a tree,or option nimber 2.You saw blossoming tree.The red colour symbolizes life and the white colour symbolizes cleanness and happiness.Anyway,your feeling about this little gift is so warm,so that it makes me look at it in different way form now on.:)Lets start a count-down.So 18 days before 1st of March.