The first 3 (healthstone, health potion and dps potion) will always show icon. If you don't have any type of those potion in your bag, it will grey out.
In DF, blizzard introduced the quality system, which is shown above the icon. If you checked the "only show highest quality" in custom options, it will show the highest quality of that potion type that you own.
Note that for dps potion, this expansion we have the cauldrons. (cauldron potion has a purple-ish boarder)
So far in beta we have two tiers,
the normal version (Elemental Potion of Power), which gives 502/577/664 main stats,
and the ultimate version (Elemental Potion of Ultimate Power), which gives 669/770/886 main stats.
If you checked the "highest quality" option for dps potions, it will prioritize cauldron potion within the same tier, regardless of their quality level.
For example, if you have a 3 star Elemental Potion of Ultimate Power, and you acquired a 1 star Fleeting Elemental Potion of Ultimate Power, this will show the cauldron version (aka. Fleeting…).