Okay... now you are asking me, a simple matchy matchy person, to be a creative person like you!

This is going to be a big and messy, but let's try this look and pull back once we see the aesthetic.
The theme here is flapper long swing... chains of Art Deco color.
The Pile On Long Necklace Look:
1) Put your 20 oynx on.
2) Next is your 20 rock crystal to act as the "white" go-between with the onyx and malachite. Oynx and malachite are severe side by side (and definitely with YG). You need something white. Hence Art Deco uses white metal with diamonds in addition to oynx and emeralds. The rock crystal is your "white".
3) Join your 10 oynx + Magic Malachite + 5 motif Malachite. You get 30". Put this on with the oynx only as filler for the back of your neck. The malachite is in the front showing.
This is going to be big busy look and only for people who like to wear three strands.
However, it's a test of color... Stare at it; see what you like, what you do not like. See if the play of the light rock crystal helps as a go-between. See if there is too much oynx? Too much malachite?
The Simpler Art Deco:
I do think you need the rock crystal as the "white" in Art Deco. Another idea:
1) Put on your 20 rock crystal.
2) Join your 10 oynx + both malachites. See if you can make the big Magic charm hang at the bottom. This should be ok to do since your eyes are blind to clasps. It's just another gold link to you!


Now you have the rock crystal as the base with a bit of oynx and a bit of malachite. Take off the rock crystal to see if you like it with just malachite and oynx.
The Long Single Necklace Flapper Look:
You could just make one long alternating oynx, malachite, rock crystal necklace. Think flapper long rope of pearls, you could try a long strand of motifs. It may be too much, but if you're the right size/shape, it may work for you.
For me, I think I may lean toward this option... a 5 oynx, a 5 malachite, a 5 rock crystal, and use your 20 oynx as the back of the neck base.
Try other options too and see if it works. It might be too busy, but you never know!