Twelve sockets, nine gem families, nine star tiers — and a combat-power number that exactly doubles at every star. Gems are the cleanest exponential in the whole game, fed by a 300-diamond crate whose odds and pity are printed right in the client.
Gems unlock at player level 25 (after clearing stage 4) and live in their own panel of 12 sockets, organized as three "cabins" of four: the Attack Cabin, Defense Cabin and Support Cabin. Each cabin only accepts its own school of gems.
The collection is a perfect grid: 9 families × 9 star tiers = 81 gems. Attack gems feed a specific weapon emitter (Maingun / Winggun / Missile), Defense gems feed the fighter (HP / Dodge / flat damage reduction), and Support gems are the counter-pick school — paired ATK-up + damage-taken-down against a specific enemy branch: air, ground/sea, or bosses ("air" explicitly includes players, i.e. PvP). The boss-counter family breaks the "Anti-X" naming — it's called the Enhancement Gem.
Values are flat numbers or percentages depending on family, but combat power is uniform: every gem of star N is worth exactly 40 × 2ⁿ⁻¹ power, from 40 at 1★ to 10,240 at 9★. A 9★ gem carries the power of 256 one-star gems — the purest doubling curve in the game.
Every family's full 1★→9★ ladder, straight from gem_def. For the flat-value families (the Attack/HP lines) the curve is back-loaded: values grow gently for seven tiers, then jump ×1.85 at 8★ and ×2 again at 9★, so ★8+★9 alone carry about two-thirds of the family's total — exactly where the grind gets steepest. The percentage families (Dodge, Defense and the Support lines) instead scale linearly 1%→9% with no end jump.
Each cabin's four sockets are wired as two pairs, and each pair pays a three-tier set bonus keyed to the total star count of the two gems in it — thresholds at 4, 8 and 12 stars (two 6★ gems max out a pair). The client's own phrasing: "Unlock after the total stars of the Gems reach {N}".
Higher-star gems come from Gem Fusion: select gems to consume and merge them upward. The UI guardrails tell you what matters — locked gems and gems socketed in other formations can't be fed in, and the client warns before you consume a high-quality gem ("The fusion will consume high quality Gem, still continue?").
The exact fusion ratio lives in the hot-update code rather than the config tables, but the power curve is the tell: with power doubling every star, any fusion that conserves value is effectively 2-for-1 per star step. On that curve, one 9★ gem embodies ≈ 32 four-star gems — or 256 crate-floor 1★ gems.
The dedicated gem crate costs 300 Diamonds per pull (or 1 Gem Crate Key), with a 10-pull at 2,600 Diamonds — a 13% bulk discount. The published odds are flat and honest: within each star band every one of the 9 families is equally likely.
The pity is generous by this game's standards: every 10th pull forces a 4★ gem (a uniform roll across the nine families). Ten pulls = 2,600 diamonds = one guaranteed 4★ plus whatever the other nine pulls yield.
Outside the crate, gems arrive as items: Random 1–4★ gem drops, school-specific randoms (Random Attack/Defense/Support Gem), and selectable 4★ / 5★ / 7★ gem packs in event shops and bundles — plus gem loot from Collection Center boxes.
gem_def (81 gems: per-star values, targets, combat power), gem_group_def (cabin pairs & set bonuses), crate odds from cfg_store row 18 + open_chest_chance chest 24 (verified equal: 50/34/12/4), pity from baodi 39 → guaranteed box 61, costs from open_chest_config 24/26/31/67, unlock from function_unlock + game_base_config.GemUnlockStage.gem_*, probability_gem*, random_gem_*).