To kill a Lich the PCs must first destroy the lich's phylactery. From the Monster's Manual we know the basic physical description of this item:
A phylactery is traditionally an amulet in the shape of a small box, but it can take the form of any item possessing an interior space into which arcane sigils of naming, binding, immortality, and dark magic are scribed in silver.
It is possible for a given item to meet the physical description of the phylactery but not yet be activity used. I.e. The lich has not yet performed the ritual to bind their soul to the item.
What methods exist for the party to determine if an item is a phylactery?
Presumably the Identify spell will do the job but is that the only way? How long does it take for a given item? Particularly can a PC check multiple items at once or do all methods require a one by one approach?
For some context imagine the following scenario.
We know that liches are very protective of their phylactery:
Because the destruction of its phylactery means the possibility of eternal death, a lich usually keps its phylactery in a hidden, well-guarded location.
Given that liches are typically highly intelligent suppose they create a room to store their phylactery. After fighting past all of the physical and magical protections on this room the party is met with a room where dozens of objects sit on pedestals.
Each of these items meets the physical description of a phylactery, but only one is the true phylactery. In order to defeat the powerful lich the party must find the correct object and destroy it before the lich can complete its evil plan.
How can the players find the true phylactery as quickly as possibly?
The main question is asking for any possible way of determining if a given item is a phylactery. If there are multiple ways, preference is for the fastest (in terms of action economy) followed by lowest resource expenditure (spell slots, 1/rest abilities, gold) and finally by earliest availability (by class level).