Yu-Gi-Oh! · Battles of Legend: Monster Mayhem

Gem-Knight Master Diamond

French name: Maître Diamant, Chevalier-Gemmes

BLMM-EN143Ultra Rare

Gem-Knight Master Diamond (Battles of Legend: Monster Mayhem BLMM-EN143) has a market price of US$0.19 as of Nov 9, 2026.

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Price guide

The market price on TCGplayer, in US dollars: a guide, not an offer.

Market price

1st EditionUS$0.19Low US$0.01

As of Nov 9, 2026 · The market price is TCGplayer’s, in US dollars. It is a guide, not an offer.

Card details

Type: Fusion Monster
Level: 9
Attribute: EARTH
Monster type: Rock
Archetype: Gem-
ATK: 2,900
DEF: 2,500

Card text

3 "Gem-Knight" monsters Must first be Fusion Summoned. Gains 100 ATK for each "Gem-" monster in your GY. Once per turn: You can banish 1 Level 7 or lower "Gem-Knight" Fusion Monster from your GY; until the End Phase, this card's name becomes that monster's original name, also replace this effect with that monster's original effects.

About this card

Gem-Knight Master Diamond is card BLMM-EN143 in Battles of Legend: Monster Mayhem, a Yu-Gi-Oh! set released Jun 13, 2025. Rarity: Ultra Rare. Finishes: 1st Edition. Reference market price on Nov 9, 2026: US$0.19. Over the last 30 days, the 1st Edition price went down 9.5%. Source: TCGplayer market data via tcgcsv.com, updated daily. A reference price is not an offer.