Category Trends
AI Market Overview
About Glass:
Our archive contains 7 appraisals in this category, with values typically ranging from a few dollars to several thousand, averaging around $220 in our dataset.
What Affects Value:
Prices are influenced by condition, age, provenance, maker/brand reputation, and collector demand. Rare, well-preserved pieces typically command higher premiums.
Price Trends
Based on InstAppraisal archive valuations
Top Brands
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| Brand | Avg Value | Trend % | Score | Demand | Volatility | Items |
|---|---|---|---|---|---|---|
| Glass | $26 | 0.0% |
56
|
2 | ||
| Green | $45 | 0.0% |
56
|
1 | ||
| Fenton | $95 | 0.0% |
56
|
1 | ||
| Murano | $600 | 0.0% |
56
|
1 | ||
| Art | $250 | 0.0% |
56
|
1 | ||
| Blenko | $500 | 0.0% |
56
|
1 |
How We Calculate These Numbers
📊 Trend Calculation
We compare average values from the last 12 months to the previous 12 months in our archive. Categories need at least 3 appraisals in each period for trend calculation.
💰 Average vs Median
Average includes all values and can be affected by outliers. Median shows the middle value, which is often more representative for categories with wide price ranges.
📈 Inflation Adjustment
Inflation-adjusted values use CPI (Consumer Price Index) data from the Bureau of Labor Statistics to show prices in today's dollars, allowing fair comparison across time periods.
🎯 Outlier Handling
We use IQR (Interquartile Range) method to identify and filter extreme values that could skew averages. Values beyond 2.5× IQR from quartiles are excluded.
🏷️ Brand Scoring
Brand trend scores combine: 40% price trend, 30% demand index (appraisal frequency), and 30% price stability (inverse of volatility).
📁 Data Sources
Archive data comes from: AI-assisted valuations, legacy appraisal prices, and verified comment values from trusted appraisers (Lovejoy, etc.).
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Data Sources & Disclaimer
About This Data
These figures reflect InstAppraisal's archive dataset — historical appraisals and derived valuations submitted by our community. Where external sold-market data is available, it's shown separately as "Market." AI-generated text provides interpretation and context only.
Data Sources
- Archive: Historical appraisals from InstAppraisal users, including AI-assisted valuations and expert comments from trusted appraisers.
- External Market: When available, sold prices from auction houses and secondary markets. Not yet connected for most categories.
- AI Overview: Generated commentary that interprets archive data — not a source of pricing data itself.
Important Limitations
- Trends are based on available data and may not represent the broader market.
- Categories with fewer than 10 items have limited statistical reliability.
- Individual item values vary significantly based on condition, provenance, and market timing.
- Historical trends do not predict future values.
This information is for educational purposes only. InstAppraisal is not responsible for buying, selling, or investment decisions made using this data.
For high-value items, consult a certified appraiser, professional auction house, or industry expert.