Noble Metal Infusions

All noble metals, in their pure forms, have a stable imbuement state which creates hard light generating micro-structures with slight affinities to certain planes. Arcsteel , an alloy of ignium , iron, and carbon (aka steel & ignium) has similar properties, but is (functionally) dimensionally neutral. Carbon actually is aligned with the human plane, but exists in quantities too low to have an impact on the overall alloy (<1% typically). The color of these light substructures tends to bleed through slightly, growing significantly brighter with additional energy input. Impurities can slightly affect this, making more impure (yet still pure enough to form the material in the first place) metals have a more 'washed out' color in most cases.
Imbuing these metals costs significantly less energy when a method aligning to their imbued state's elemental affinity is used. Fire for embergilt, blood sacrifice for orichalcum, and so on. Such affinities do not change based on the current position's planar convergence set. Copper remains Blood-aligned even though Blood isn't a greater plane on the continent etc.

Phantom-Adamantine Effect

All noble metal infusions exhibit the phantom adamantine effect, in which channelling magical energy through them generates hard light substructures which reinforce the material, along with causing some unusual behavior in motion. Phantom Adamantine Effect
Note that noble metal infusions don't oxidize, unlike their base counterparts. A flow of magical energy in most pure metals will prevent oxidation, and the latent hard light substructures naturally introduce a minor flow of magical current.

The Metals

Copper- Orichalcum (Blood)

Glows red.
More widespread before steel production techniques. Relatively poor mechanical properties (roughly equivalent to bronze, though less brittle), but excellent energy retention and discharge rate makes it ideal for capacitors. Self-healing makes it useful for medical applications.

Silver- Moonsilver (Darkness)

Glows blue.
Used in several types of Cotd weaponry. The Abyss Dwellers have access to far more interesting materials, namely hemite and abyssium. They do use it for jewelry quite often though, being more durable (and not tarnishing) than ordinary silver.

Gold- Embergilt (Fire)

Glows orange.
Embergilt. Comparable to bronze when unreinforced, popular within the midlands. Very high reinforcement ratio- famous for its blades supposedly being able to cleave through plate armor when wielded with sufficient strength of will.

Mercury- Mithril (Storms)

Glows cyan-purple.
Past the imbuement threshold, the material 'locks' into place as a solid mass. The newly created substance has some give to it, but sufficient force to break part of it will cause the entire thing to shatter like tempered glass, converting back to liquid mercury in the process.

Platinum- Slade

Glows pale yellow.
The material is far more durable than even alvahedi, even in its resting state, and around 9 times as dense as the platinum that it is created from. Additionally, it is noticeably darker than ordinary platinum, reminiscent of magnetite (although far glossier).
Slade is so durable that it's functionally impossible to actually work the material- to alvahedi what alvahedi is to copper.

Palladium- Phasegleam

Glows green.
Imbued palladium is invisible to magical energy- said energy can pass through it as if it were vacuum, and cannot directly influence it. By the same token, it cannot be directly influenced by magical energy. This of course makes the imbuement process very tricky. Once the metal reaches its imbuement threshold, it suddenly becomes magically invisible and its stored energy diffuses- the only way to maintain its higher state is to keep ambient energy levels high enough to imbue the metal. This is theoretically a great way to regulate the flow of magical energy, but the metal is prohibitively expensive. In the imbued state, it acts like a pseudo-hard light: resisting incoming forces by drawing from an energy source (in this case, the ambient energy it's submersed in), along with infinite specific heat.
Being magically invisible, the material has no volatility limit. No other physical substance exhibits this property (though admittedly, slade's volatility limit can't meaningfully be reached without destroying the world).

Alloying

Alloys often behave in strange ways, exhibiting parts of the original noble metal's abilities to varying degrees. It's hypothesized that they 'tint' the magical signature of a material when below the coherency limit, imparting lesser versions of their effects. Blending the materials in the first place tends to require some sort of repeated folding process so that the effects can cross-link between layers (whereas the coherency limit would disperse them if just mixed in). Exceptions to this are alloys of several noble metals, such as triavanium, which will spread their effects evenly.

Rankings

Imbuement Threshold

Amount of energy required to change a metal into its imbued state.
Highest
Platinum
Copper
Gold
Mercury
Silver
Palladium
Lowest

Energy Bleed

Rate at which energy past the imbuement threshold bleeds out. Sort of like thermal conductivity. Faster means worse retention.
Highest
Gold
Palladium
Silver
Mercury, Copper
Platinum (effectively zero)
Lowest

Reinforcement Ratio

Amount which a material is reinforced per unit of energy input past imbuement threshold.
Highest
Gold
Mercury (technically indestructible until it's not, but the 'not' point is less than gold's reinforcement)
Silver
Copper, Palladium
Platinum (relative to its imbuement threshold, the ratio isn't much worse, it's just that it takes so much energy to imbue)
Lowest

Baseline Properties

Mechanical properties of the baseline imbued state (no extra charge). They all tend towards something similar to tempered steel: strong, hard, but relatively brittle, so a linear ranking makes sense. Note that infused copper (orichalcum) is unsually flexible.
Strongest
Platinum (essentially immutable)
Mercury (technically indestructible until it's not, though exhibits some give, which puts it below platinum)
Gold
Silver, Copper, Palladium
Weakest