{"tiers":[{"tier":1,"grade":"F","name":"Grade F","share":"most common materials (top ~22% cumulative weight)"},{"tier":2,"grade":"E","name":"Grade E","share":"next ~17% cumulative weight"},{"tier":3,"grade":"D","name":"Grade D","share":"next ~24% cumulative weight"},{"tier":4,"grade":"C","name":"Grade C","share":"next ~27% cumulative weight"},{"tier":5,"grade":"B","name":"Grade B","share":"next ~9.5% cumulative weight"},{"tier":6,"grade":"A","name":"Grade A","share":"next ~0.4% cumulative weight"},{"tier":7,"grade":"S","name":"Grade S","share":"rarest materials (bottom ~0.1% cumulative weight)"}],"note":"tier is determined solely by material grade — each material maps to a tier via cumulative weight share cutoffs","gradeRanges":{"tools":23,"wearables":30}}