It would help me to know what one looks like so I can pick it up.

An artifact is a white crystal, but what does a relic look like?

Something like this.

LOL Tom

Each relic looks different. From Stella's:

Artifacts look like shiny statuettes with a different design for each game location (e.g., Tyrannosaurus teeth in Peru, spearheads in Greece, cartouches in Egypt, carved idols in Atlantis). Relics are unique items. Each has a different appearance and description. You'll see an information screen about each relic when you find it. You can also examine the relics you've found so far in the Rewards section of the main menu, or by visiting Lara's trophy room in Croft Manor.

The one in the mountain caves is a bottle. I think this is it:

LOL Tom

Each relic looks different. From Stella's:

Artifacts look like shiny statuettes with a different design for each game location (e.g., Tyrannosaurus teeth in Peru, spearheads in Greece, cartouches in Egypt, carved idols in Atlantis). Relics are unique items. Each has a different appearance and description. You'll see an information screen about each relic when you find it. You can also examine the relics you've found so far in the Rewards section of the main menu, or by visiting Lara's trophy room in Croft Manor.

The one in the mountain caves is a bottle. I think this is it:

That doesn't look like any bottle I've seen before.

Yeah, same here

Here's the full description of it:

I'll just take CD's word that it's a bottle