The color change will last until you reverse the temperature. Note that the temperature of your fingers or body can be warm enough to affect the color.
The temperature of the water should be either ice cold (59 degrees or below) or very warm (95 degrees or above) to change the color of the jewels. Make the ice water colder with ice or heat the warm water to get the right temperature.
* Note that the small round beads do not change color.
Do not dip for too long.