I made a ring based on the colour themes of the Yakumos. Chen is in an orange sapphire (had issues with citrine and spessartite), Ran is in the closest-to-indigo-I-could-get sapphire, and Yukari is in an amethyst. Set in sterling silver naturally.
This one was very subtle and the person who got it has no idea of what went into the design, which is also why I hesitated a bit around posting it. My next bit of jewellery work will not be.