Cheapest way to make C crystals with duals=>cryst?

I've noticed that the price of C crystals when buying 2 D grade weapons and making duals then crystalize can vary.
So what pair of D weapons has best value for making C crystals?

Elven.

When taxes were low I remember buying lots of them, cheapest way to get c crys I think.

when taxes are high, dual Crimson.

Uhm,

Elven*Elven 784 C crys, Crimson*Crimson 784 C crys

Elven Sword 1758 D crys, Crimson Sword 1758 D crys.

They should cost the same if im right, do crimson dual cheaper?

dul crimsons and dual elvens give exactly the same result. as do saber*sor. but saber*sor cost more to dual.

in order, the lowest crystal yeild per dual is as follows:
crimson*crimsons / elven*elven / saber*SOR = 784
knights*SOR / bastard*SOR / Spinebone*SOR = 858
Saber*ELS = 916
Elven*SOR / Crimson*SOR = 988
Artisan*ELS / Spinebone*ELS / Bastard*ELS /Knights*ELS = 988 (cheaper cost to dual)
Crimson*ELS / Elven*ELS / Sor*Sor = 1148
SOR*ELS = 1336
ELS*ELS = 1528

those are the YIELD amounts. since cost varies based on tax, youll see C crystals by dualling D swords at their cheapest on the LOWEST yield duals. this can vary between 3010 adena per crystal to 3567 at poorly taxed cities.

remember: the HIGHER the tax rate is, the LOWER the D weapon cost (and consequent C crystal price) is.

as my server has a mid tax of 15%, we see C crystals in sell shops for 3300~ usually.

What about d-crystals. Which duals or weapon/armor in general are the best?

What about d-crystals. Which duals or weapon/armor in general are the best?

Doesn't matter.

Elven necklace IMO, on Gustin, taxed 3-5% Giran-Heine they are usually 672a.