From astrological point of view there are certain gemstones that should not be worn together.
| Gemstones | Ruling Planet | Anti-Gemstones |
|---|---|---|
| Ruby | Sun | Diamond, Garnet, Blue Sapphire |
| Pearl | Moon | Garnet |
| Coral | Mars | Diamond, Garnet, Blue Sapphire |
| Emerald | Mercury | – |
| Yellow Sapphire | Jupiter | Blue Sapphire, Diamond |
| Diamond | Venus | Ruby, Yellow Sapphire, Coral |
| Blue Sapphire | Saturn | Ruby, Yellow Sapphire, Coral |
| Garnet | Dragon’s Head (Rahu) | Ruby, Coral, Pearl |
| Cat’s Eye | Dragon’s Tail (Ketu) | – |
I hope this answers your question.