Test 8

A good appraisal isn’t a hunch—it’s a structured investigation. Whether you’re a professional appraiser, a dealer, or an advanced collector, a repeatable method is the surest way to reach reliable conclusions. This guide lays out eight core tests that, used together, help you authenticate and value antiques and artworks, and documents how to turn those findings into a defensible report.

Why a test-based method works

Antiques and art are complex: objects travel, get altered, inspire copies, and move through volatile markets. A single data point—an inscription, a bill of sale, or one auction comp—rarely settles the matter. A test-based method forces you to:

• Seek corroboration from multiple lines of evidence.
• Separate what you know from what you assume.
• Quantify condition and risk in the value conclusion.
• Communicate scope, limitations, and confidence clearly.

The eight tests below aren’t performed in strict sequence; in practice, you’ll loop through them as new evidence reframes earlier assumptions.

The eight tests of authenticity and value

1) Provenance and ownership chain

• Aim: Establish lawful ownership and contextualize authenticity.
• What to gather: Bills of sale, invoices, exhibition labels, collection stamps, estate inventories, shipping records, export permits, restoration invoices, photography with dateable environments.
• Quality test: Unbroken, document-based chains are strongest; gaps aren’t fatal if other evidence is strong. Beware freshly “discovered” documents that perfectly solve a value problem.
• Special periods: For European art, scrutinize 1933–1945 gaps. For archaeological items, look for pre-1970 collecting histories. For ivory or tortoiseshell, confirm pre-ban dates or exemptions.

2) Materials and construction

• Aim: Verify that materials and methods match the alleged time, place, and maker.
• Furniture and objects: Check wood species (oak vs. mahogany vs. softwood secondary), hand-sawn vs. machine-sawn marks, dovetail angles and spacing, tool marks, screw and nail types, glue residues (animal glue vs. PVA), veneer thickness, finish layers.
• Paintings: Support type (panel, canvas), weave pattern, ground color and texture, stretcher/strainer features, tacking margin evidence.
• Ceramics and glass: Paste/body type, glaze, pontil finish, mold seams, anneal marks, stratified weathering.
• Metals: Alloy composition, casting seams, cold work traces, fasteners, patination type and penetration.

Match the “grammar” of construction to the claimed period. A Georgian chest of drawers with uniform machine-cut dovetails and Phillips screws is unlikely to be 18th century.

3) Signatures, marks, and inscriptions

• Aim: Treat markings as data to confirm or challenge attribution—not as proof.
• Procedure: Compare to verified exemplars; assess typical placement, tool, and execution speed. Look for aging congruent with surrounding surfaces (ink sink, paint craquelure continuity, oxidation within incisions).
• Common pitfalls: Transferred or reinforced signatures; added “Made in…” marks to fake export eligibility; married lids with desirable maker marks; “period appropriate” but modern stamps.
• Documentation: Photograph under raking light and magnification. Record measurements and exact location.

4) Style, attribution, and workshop practice

• Aim: Fit the object into a stylistic and workshop map.
• Connoisseurship: Analyze design vocabulary, proportions, iconography, and technical choices. For artists with catalogues raisonnés, check known variants and studio patterns. Consider “autograph,” “studio of,” “follower of,” “circle of,” “manner of,” and “after”—each with different value implications.
• Regional signals: Provincial vs. metropolitan making, trade routes for materials, guild rules affecting construction.
• Coherence test: The object’s style, materials, and claimed provenance should tell the same story; if one element is discordant, investigate why.

5) Wear, surface, and interventions

• Aim: Distinguish honest age from artificial aging and document condition.
• Natural aging: Oxidation gradients, grime accumulation, surface micro-abrasion, softening of sharp edges in high-contact zones, shrinkage and checking in wood, craquelure patterns consistent with ground and paint layers, glass devitrification in archaeological contexts.
• Red flags: Uniform “wormholes” that ignore structural logic, edge chipping that doesn’t match fracture physics, fresh tool marks hidden under tinted wax, “antique” finishes that sit on top of later repairs, over-cleaning that erases tool chatter.
• Interventions: Overpaint, relining, replaced hardware, patching, regilding, reconversion (e.g., candlesticks to lamps), new mounts. Note stability and reversibility; conservation quality influences value.

6) Scientific diagnostics and safe testing

• Aim: Use objective methods to confirm materials and chronology.
• Non-invasive first: UV-induced fluorescence (varnish, overpaint), infrared reflectography (underdrawing, pentimenti), raking light (surface topology), X-ray radiography (construction, earlier compositions), handheld XRF (elemental composition of metals, pigments, glazes), microscopy (tool marks, pigment particle morphology).
• Invasive only with consent: Dendrochronology for panel supports, thermoluminescence for fired ceramics, radiocarbon for organic materials, cross-section paint analysis, metallography. Obtain written permission; explain sampling location and risks.
• Interpretation: Tests answer specific questions; they do not authenticate in isolation. For example, a 19th-century pigment in a “17th-century” painting is disqualifying; period pigments do not prove authorship.

7) Market literacy and regulatory filters

• Aim: Understand where the object can legally and practically sell, and how that affects value.
• Legal and ethical screens: Cultural property laws, export controls, CITES restrictions (ivory, tortoiseshell, some rosewoods), protected species in inlay, NAGPRA considerations, WWII-era restitution claims. Document due diligence.
• Market segments: Dealer retail, auction (regional, national, international), private treaty, trade/wholesale. The appropriate venue depends on price level, risk, and audience specialization.
• Liquidity and timing: Seasonality, current collecting taste, artist market cycles, macroeconomic conditions. Thin markets magnify risk and widen value ranges.

8) Coherence and risk rating

• Aim: Synthesize findings into a coherent narrative with an explicit confidence level.
• Internal consistency: Do provenance, materials, marks, style, and condition align? If not, state which tests carry more weight and why.
• Risk factors: Attrition risk (hidden condition issues), legal risk (export, restitution), attribution risk (competing opinions), and market risk (volatility). Assign qualitative ratings (low/medium/high) and reflect them in value ranges and intended use.

Comparables and value conclusion

A value conclusion is only as strong as the comparables behind it. Build comps that mirror the subject on the variables that matter most to buyers in the relevant venue.

• Define the value type:

  • Fair Market Value (FMV): The price between willing buyer and seller, neither under compulsion, both informed, in the most relevant market.
  • Retail Replacement Value (RRV): The cost to replace with a similar item at retail in the ordinary course of business, used for insurance.
  • Liquidation values: Orderly (time-limited but not rushed) vs. forced (most compelled sales), usually lower than FMV.

• Choose the market: For FMV, look at recent, arm’s-length sales in the market where the item would most likely transact. For RRV, use dealer asking and documented retail sales; be cautious with inflated list prices—seek evidence of actual selling.

• Select comparables:

  • Same or closely related maker/attribution level (“by,” “attributed to,” “school of”).
  • Similar period and geography.
  • Comparable size and format (e.g., oil on canvas 24x36 in; not a print vs. a painting).
  • Similar condition state and conservation history.
  • Comparable provenance significance (ex-museum or notable collection may carry premiums).
  • Similar subject matter for artworks (portrait vs. landscape) and function for objects (highboy vs. chest-on-chest).

• Normalize and analyze:

  • Sale terms: Distinguish hammer price from price including buyer’s premium; note currency and convert using the rate at sale date.
  • Date sensitivity: Older comps may need less weight in fast-moving markets; for stable categories, longer windows are acceptable.
  • Adjustments: Note directional adjustments (up/down) for condition, size, and provenance. Avoid formulaic area-based scaling for paintings; sensitivity is often non-linear and artist-specific.
  • Outliers: Identify record-setting or distress sales and explain whether you include or exclude them.

• Conclude with a range: Provide a reasoned range rather than a single point when attribution or market volatility warrants it. Tie the range explicitly to the risk rating from the coherence test.

Example synthesis (structure, not a real object): “Based on three closely related signed works from 1910–1912 sold at international auction between 2021 and 2024, adjusted downward for scattered overpaint and a smaller format, and upward for documented exhibition history, the FMV is concluded at $120,000–$160,000 with moderate attribution risk.”

Ethics, law, and reporting clarity

Even impeccable analysis fails if the report is opaque or ethically compromised.

• Scope of work: Define what you examined, methods used, and what you did not or could not do (e.g., “No paint samples taken; UV and IR imaging performed”).
• Intended use and users: Insurance scheduling, charitable donation, estate tax, equitable distribution, resale advice—each may require different value definitions and comparable sets.
• Assumptions and limiting conditions: Note extraordinary assumptions (e.g., “Assumes the signature is autograph; no lab testing performed”) and their effect on value.
• Conflicts and independence: Disclose prior dealings with the object, owner, or potential buyers. Avoid contingent fees or fee structures tied to value outcomes.
• Compliance: Align with recognized standards (e.g., USPAP) where applicable; retain workfiles with notes, images, and sources.
• Legal hygiene: Verify you have authority to appraise; for cross-border items, check export/import compliance. Document your due diligence even when results are negative (“no evidence found of WWII-era loss”).

Field checklist (concise)

• Before the visit:

  • Request all prior appraisals, invoices, restoration records, and provenance documents.
  • Clarify assignment type, value definition, intended use, and deadline.
  • Pack tools: 10x loupe, UV flashlight, measuring tape, scale, calipers, magnet, flashlight, handheld XRF (if trained), gloves, camera, color checker, raking light source.

• On-site examination:

  • Photograph all sides, details, labels, and marks; include scale references.
  • Measure dimensions and weight; note construction features and materials.
  • Test under UV and raking light; note fluorescence and surface topology.
  • Record condition systematically: structural, surface, alterations, prior restoration.
  • Document any inscriptions, signatures, and labels; sketch placement.

• Research and analysis:

  • Verify maker marks against references; check catalogues raisonnés where relevant.
  • Build a provenance timeline; flag gaps and sensitive periods.
  • Compile 5–10 candidate comparables; filter to the best 3–5.
  • Assess regulatory issues (CITES, export controls, cultural property).
  • Draft a coherence and risk summary; determine need for lab testing.

• Reporting:

  • State scope, methods, assumptions, and limiting conditions.
  • Present comparables with sources, dates, prices, and rationale for inclusion.
  • Conclude with value type, range or point, effective date, and confidence notes.
  • File all work product (photos, notes, correspondence) for auditability.

FAQ

Q: How many comparables do I need for a defensible value? A: Quality beats quantity. Three to five well-matched comps, explained clearly with adjustments and exclusions, are usually stronger than a dozen loosely related sales.

Q: Should I ever clean or test an object before appraisal? A: Do not clean, polish, or perform invasive tests without written consent. Surface residues and tool marks are evidence. Start with non-invasive imaging; propose sampling only if it could materially change attribution or value.

Q: What’s the difference between “attributed to” and “circle of”? A: “Attributed to” indicates a reasoned opinion that the work is likely by the named artist but with some uncertainty. “Circle of” suggests a contemporary working in the artist’s orbit, not necessarily the studio; value implications are markedly different.

Q: Can a strong provenance overcome weak materials evidence? A: Rarely. Provenance can be forged or mistaken. Materials and construction inconsistent with the claimed period are usually decisive. Strong cases show alignment across provenance, materials, style, and condition.

Q: When should I use a range versus a single value? A: Use a range when attribution is not fully resolved, market data are thin, or risks are elevated (legal, condition, or volatility). A single point is appropriate when evidence is robust and market comparables are close.