**TL;DR: Does the Celestial Armor require medium armor proficiency?**

I found the [Celestial Armor](https://www.d20pfsrd.com/magic-items/magic-armor/specific-magic-armor/celestial-armor/) which said that it is a **medium armor** [Chainmail](http://www.d20pfsrd.com/equipmenT/armor/chainmail)+3, and is light enough to be considered as **light armor**.

But, does it work just like a [Chainmail](https://www.d20pfsrd.com/equipment/armor/chainmail/) made from [Celestial Mithral](http://www.d20pfsrd.com/equipment-/special-materials#TOC-Mithral), which then makes the armor light enough to be considered as **light armor**, but still requires **medium armor** proficiency? After all, it does seem to be made from it, even if it doesn't state it.

When checking other armors, I found the [Elven Chain](http://www.d20pfsrd.com/magic-items/magic-armor/specific-magic-armor/elven-chain/) which state that it is a [Chainmail](https://www.d20pfsrd.com/equipment/armor/chainmail/), but should be considered as **light armor**, even from the proficiency point of view. But it also state that it is made from **Mithral** unlike the [Celestial Armor](https://www.d20pfsrd.com/magic-items/magic-armor/specific-magic-armor/celestial-armor/).