Every tradeable Chambers of Xeric unique, indexed to its price at the start of the window.
Each line is rebased to 0% at its own price when the selected window starts (the dashed line) — not raw GP, since these items range from ~1m to ~1b+. A line at +50% means that item is 50% more expensive than it was at the start of the window; it says nothing about its price relative to any other item.
Chambers of Xeric uniques only enter the game as raid drops, so their supply is set by how many raid teams are clearing the room per day — not by a shop or a fixed drop source players can farm on demand. A price move across the whole set at once usually means something changed about how many teams are running CoX (a difficulty change, a new strategy going public, a content creator spike) rather than anything about one item specifically.
Every line on this chart is indexed to its own price at the start of the window, not plotted in raw GP — a Twisted bow and a Twisted buckler are hundreds of times apart in price, so the raw numbers would flatten everything but the bow into a line along the bottom of the chart.
