Reading the room, one lot at a time.

• Christie's and Sotheby's — the reference sales for major art, jewels and select instruments.
• Phillips — strong on 20th-century and contemporary; increasingly on watches and design.
• Tarisio — the specialist house for fine violins, violas, cellos and bows.
• Bonhams — broad, useful for European decorative arts and furniture.
• Ansorena and Alcalá — the principal Spanish houses; relevant for Iberian art and antiques.

Auction catalogues are written in a careful, coded language. "Attributed to" is not "by". "In the style of" is not "attributed to". Condition reports are the most useful document — request them, read them, and if a lot matters, arrange a private viewing.

See Best European auction houses for rare instruments.

Truly great instruments and truly great pictures often move privately — either through a house's private sales desk, through a dealer, or through a direct introduction. Auction is the visible market. It is not the whole market.