When the gems are idle in a game of Bejeweled they like to do a shine (or reflect?) effect. Is that something that must be animated on the art side or is it possible to use a shader to generate this effect?
If you’re using sprites, then it should be done on the art side, and merely have your script for the jewel trigger the shine animation after delta.time has reached a certain threshold, and reset the counter when that happens or if it’s interacted with.
If it’s a 3D model, then you could use a shader that has specular and merely increase it’s value like you would trigger an animation in the previous method. Though this effect wouldn’t look that great unless you had a good enough model and lighting setup, preferably an environment map for the shader. All depends on the look you’re going for.