Artifact relics are Legion-era items that slotted into artifact weapons rather than gear sockets, so their market is historical Retail inventory. This page narrows Gem down to Artifact Relic only, so the table stays scoped to one subtype instead of the full category list.
Artifact Relic listings clear and replenish at whatever pace the in-game market sets; some subtypes trade in volume, others sit static for stretches. The price-history chart on each row's detail page makes that pattern visible at a glance.
If you want the full Gem category rather than only Artifact Relic, the breadcrumb above steps back up one level; otherwise the table below covers every tracked item in this subclass.