Before patch 3.1 when you inspected others, it would perfectly show the metagem highlighted for them if the gem requirement were met,
granted that the tooltip was being shown using GameTooltip:SetInventoryItem(unit,slotId).
Ever since the patch though, gems and meta gems for inspection has been bugged and will not show up correctly.
Gems does load after about 0.25 seconds (latencty may come into play here), but meta gems stay grayed out.