Why has my moonstone started turning Blue?

Does anyone know what it means now that my favorite new moonstone pendant has started to turn blue?

I bought it a month a go..very beautiful it is tear-dropped in 2 pieces.. the lower piece closest to my heart has started to take on beautiful blue tones and actually gleams more now. At certain times, it is almost all blue but then go back to normal hues.

Thanks
Be Calm Through the Storm & stay always in the light. . .
In Faith, Hope & Love,
Gina