Related Clues:

• Not to be had
• Bibliophile's label
• One-in-a-million
• Far from frequent
• Of interest to collectors, say
• Chophouse request
• Pastel shade
• Reef buildup
• Atypical
• Marine formation
• Quite unusual
• Pink hue
• Like a 1943 copper penny
• Out of the ordinary
• Facing extinction