A few crystals that are recommended to not be paired

Acquiring a crystal can promote physical, spiritual, and mental healing. 
Some crystals repel negative energy, boost your mood, calms you down, amplify your energy, motivate you, interact positively with your body’s chakra, alleviate stress, ignite creativity, and many more.
Crystals and Gemstones are fascinating and beautiful. Each stone possesses different natural earth vibrations and therefore energies and feelings when in our possession; as well as metaphysical properties linking with the colours and chakra associated; that many have spent years researching.
In theory, their energies can repel and supplement other crystals. That’s why a few specific stones shouldn’t really be paired together. 

Carnelian & Amethyst
Carnelian boosts a person’s energy, while Amethyst calms your energy down. This means that they will cancel each other out and send a confusing signal to our chakra’s. 
As a result, you will feel uncomfortable and uneasy because your chakra would be confused if they would boost your energy or calm you down.  

 

Blue Lace Agate & Red Jasper
When people may be depressed, they may use their Red Jasper crystal to boost their energy together with a Blue Lace agate to calm them down and slow down their emotions. Little did they know, combining Red Jasper with Blue Lace agate when you are depressed isnt a great match. 
Red crystals are known to amplify your energy, and if you have low energy, a red crystal could boost low energy, which in turn could leave you maybe feeling a little more low.

 

Sunstone & stones associated
with Saturn or Venus. 
To unleash the full capacity of sunstone, avoid mixing them with antagonistic stones with vibrational frequencies. If you have rubies, don’t mix them with garnet, sapphires, and diamonds because they don’t work well together.

 

Gomed HESSONITE and Cat’s eye
Rahu and Ketu in Hindi folklore should not be placed side by side. Gomed is a powerful gemstone of planet Rahu and Cat’s eye represents planet Ketu. If you have a Gomed and a Cat’s Eye side by side, it is like you are inviting negative energy effects to your life. It could bring over indulgence, illness, restlessness or other nasty negatives into your life. Not a good mix.

All of the above are advisory’s - please use your own knowledge, research and common sense when selecting the correct crystals for yourself.