Introduction
The auction room is where the antique glass market sets its prices, establishes its benchmarks, and — for the informed buyer — offers some of its best opportunities. For the collector of 18th-century English drinking glass, the major specialist glass sales at the leading auction houses are essential reference points, whether or not you intend to bid. They are where the rarest and finest pieces come to market, where condition and attribution are scrutinised most rigorously, and where the cumulative knowledge of the specialist glass world is most concentrated.
But auctions can also be intimidating, particularly for the new collector, and the consequences of buying badly — overpaying for a damaged piece, missing a condition issue, or misreading an estimate — can be significant. This guide sets out what to look for, what to ask, and how to approach the auction process with confidence.
Which Auction Houses to Watch
Not all auction houses are equal when it comes to antique glass. For serious collecting, the following are the most relevant:
Specialist Glass Sales
- Bonhams — holds periodic specialist glass and ceramics sales with strong coverage of 18th-century English drinking glass. Catalogue descriptions are detailed and condition reports are generally reliable.
- Roseberys London — a mid-tier London house with regular decorative arts sales that frequently include good quality English glass. Often offers better value than the major houses for mid-range pieces.
- Christie's and Sotheby's — the major houses handle the finest and rarest pieces, typically as part of broader decorative arts sales rather than specialist glass sales. Important for establishing top-end market values.
Regional and General Sales
Regional auction houses — particularly those in areas with strong antiques traditions (the Cotswolds, East Anglia, the West Country) — regularly include antique glass in their general sales. These can offer excellent value, particularly for buyers who are willing to do their own research and travel to view. The trade buys heavily from regional sales, and the collector who does the same is accessing the same source material.
Online Auctions
Platforms such as the-saleroom.com, i-bidder.com, and individual house online bidding platforms have made auction buying significantly more accessible. However, buying glass online without viewing in person carries real risks — condition issues that would be immediately apparent in the hand are easily missed in photographs. Online buying is best reserved for pieces where the risk is proportionate to the price, or where you have a high degree of confidence in the cataloguing of the specific house.
Before the Sale: Research and Preparation
Study the Catalogue
Auction catalogues for specialist glass sales are invaluable documents. Read the catalogue description carefully — specialist cataloguers use precise language, and the specific terms used to describe a piece carry meaning. Note in particular:
- The stem description — the cataloguer's identification of the stem type, knop forms, and twist configuration is the primary basis for attribution and dating.
- The condition report — most houses provide condition reports on request, and specialist sales often include condition notes in the catalogue entry itself. Read these carefully; they are where chips, cracks, repairs, and other issues are disclosed.
- The estimate — the pre-sale estimate reflects the cataloguer's assessment of likely hammer price based on recent comparable sales. It is a guide, not a guarantee — popular pieces regularly exceed their estimates, and unpopular ones may sell below.
- Provenance — any collecting history noted in the catalogue entry adds confidence and, for significant pieces, value. A piece from a named collection — particularly one with a long history in the specialist glass world — carries additional weight.
Request a Condition Report
For any piece you are seriously considering, always request a full condition report from the auction house before bidding. Most houses will provide these on request, and specialist departments will often answer specific questions about a piece — the quality of a twist, the character of the pontil mark, the nature of a repair. Do not rely on catalogue photographs alone for condition assessment.
Attend the View
The pre-sale view — typically held in the days before the sale — is your opportunity to handle the pieces you are interested in. This is essential for serious bidding. No photograph, however good, conveys the weight, resonance, and physical character of a glass. Bring a loupe. Examine the pontil mark, the foot rim, the bowl rim, and the engraving (if any) under magnification. Assess the weight and resonance. Look at the piece from every angle.
If you cannot attend the view in person, consider asking a trusted dealer or fellow collector who is attending to examine the piece on your behalf. Many specialist dealers will do this as a professional courtesy, particularly if you have an existing relationship with them.
Understanding Estimates and Reserves
The pre-sale estimate is the range within which the cataloguer expects the hammer price to fall, based on recent comparable sales and their assessment of the piece's quality and condition. It is important to understand what the estimate does and does not tell you:
- The estimate does not include the buyer's premium — the percentage added to the hammer price that represents the auction house's fee. Buyer's premiums at the major houses typically run to 25–28% of the hammer price (plus VAT on the premium). Always calculate your maximum bid on the basis of the total cost including premium, not the hammer price alone.
- The estimate reflects the cataloguer's view of the market at the time of cataloguing. If comparable pieces have sold strongly since the catalogue was prepared, the actual result may exceed the estimate significantly.
- The reserve — the minimum price below which the piece will not be sold — is typically set at or just below the lower estimate. A piece that fails to reach its reserve is ‘bought in’ and may be available for private purchase from the house after the sale, sometimes at a negotiated price.
Condition: What to Look For
Condition is the single most important factor in the value of an antique glass, and condition assessment is the skill that most repays development in the new collector. The following are the key areas to examine:
The Bowl Rim
The most vulnerable point of any drinking glass. Examine the rim carefully under good light, rotating the glass slowly. Even a small chip — 1–2mm — significantly affects value. A rim that has been ground down to remove a chip will be slightly thicker and less sharp than the original; the proportions of the bowl may be subtly altered. Run a finger lightly around the rim to feel for any irregularity.
The Foot Rim
The second most vulnerable point. Chips to the foot rim are common and, depending on their size and position, may or may not significantly affect value. A single small chip to the foot rim of an otherwise fine piece is less serious than a chipped bowl rim; multiple chips or a large chip are more significant.
Cracks
Any crack in a glass — however fine — is a serious condition issue. Examine the bowl, stem, and foot carefully in transmitted light (holding the glass up to a window or light source) to reveal fine cracks that may not be visible in reflected light. A crack that runs through the stem is particularly serious, as it compromises the structural integrity of the piece.
Repairs
Repairs to antique glass — typically involving the use of adhesive to reattach a broken component or fill a chip — should always be disclosed in the condition report. Examine junctions between components carefully for evidence of adhesive. Under ultraviolet light, many adhesives fluoresce, revealing repairs that are invisible in normal light. Some auction houses will UV-examine pieces on request.
Crizzling
Crizzling — a form of internal glass deterioration caused by an imbalance in the glass formula — is found on some early English glasses, particularly those produced in the period immediately following Ravenscroft's development of lead crystal, when the formula was not yet fully stabilised. It manifests as a network of fine internal cracks or a cloudy, iridescent surface. Crizzling is progressive and cannot be reversed; a crizzled glass will continue to deteriorate over time. See our companion guide Crizzling in Early English Glass for full detail.
Engraving Condition
On engraved pieces, assess the sharpness and completeness of the engraving. Worn or partially abraded engraving reduces value; missing elements of a design — a lost bud on a Jacobite rose, a worn motto — are significant. Also assess whether the engraving is period or later — see our companion guide Spotting Later Engraving on Antique Glass.
Bidding Strategy
Set a Maximum Before You Bid
Decide your maximum bid — including buyer's premium and VAT — before the sale begins, and stick to it. The atmosphere of the auction room, and the competitive dynamic of bidding, can easily push buyers beyond their intended limit. A piece bought at twice its value because of auction fever is not a bargain.
Absentee and Telephone Bids
If you cannot attend the sale in person, most houses accept absentee bids (a maximum bid left with the house, which will bid on your behalf up to that limit) and telephone bids (a specialist will call you during the sale and bid on your behalf in real time). Telephone bidding is preferable for significant pieces, as it allows you to respond to the room and make a final decision in the moment.
Online Bidding
Most houses now offer live online bidding through their own platforms or through aggregators such as the-saleroom.com. Online bidding carries a small additional premium (typically 3–5%) on top of the standard buyer's premium. Factor this into your maximum bid calculation.
After the Sale: Bought-In Pieces
Pieces that fail to sell — bought in because they did not reach their reserve — are often available for private purchase from the house after the sale. If a piece you wanted was bought in, contact the specialist department promptly. The house will typically approach the vendor with any serious offer, and bought-in pieces are sometimes available at or below the lower estimate.
Building Auction Knowledge Over Time
The most valuable thing a collector can do — beyond any individual purchase — is to attend sales regularly, handle pieces at views, and track results over time. Auction results are published by the major houses and aggregated on platforms such as the-saleroom.com, providing a searchable record of what comparable pieces have sold for and when. This accumulated knowledge of the market — what things are worth, what condition issues affect value, what the current collecting trends are — is the foundation of confident buying.
The collector who attends views regularly, handles pieces systematically, and tracks results over time will develop an eye and a market sense that no guide can substitute for. The auction room, approached with preparation and patience, is one of the best schools in the world for the serious collector of antique glass.
The Wonder Room offers a carefully selected range of antique drinking glasses, each described honestly and in detail. Browse our current collection or explore further guides in Collector's Insights.