How We Evaluate Your Precious Metals
Step-by-Step Precious Metal Appraisals in Portland
At Portland Gold Exchange, transparency is at the core of our values as a trusted local precious metals buyer. Our evaluation process empowers you with clear information so you can make confident, informed financial decisions. Conducted directly in front of you at our Milwaukie Avenue storefront, a typical appraisal takes between 15 and 30 minutes (with additional time allocated for larger collections or estate lots).
If you have questions about our testing procedures or wish to speak with an analyst, call us directly at (503) 954-1480.
Step 1: Initial Metal Testing (Magnet Screening)
The appraisal begins by screening all items with a strong earth magnet. Because authentic gold, silver, and platinum are non-magnetic, this fast preliminary step immediately separates base metal pieces from items that contain precious metals.
Step 2: Sorting by Karat, Fineness & Hallmark Inspection
After separating magnetic base metals, items are sorted by karat purity and fineness:
- Hallmark Loupe Inspection: Analysts examine each piece for stamped hallmarks (such as 10k, 14k, 18k, or 3-digit fineness marks). For tiny, worn or hard-to-see stamps on earring posts or ring interiors, we utilize a jeweler's loupe.
- Understanding Karats and Fineness: Karat measures gold purity out of 24 parts (24k = pure gold), while fineness measures purity in parts per 1,000.
For example, 583/1000 fineness equals 14k gold (58.3% pure) and 750/1000 fineness equals 18k gold (75.0% pure). - Sorting Grid Organization: Because stamped hallmarks are a helpful indicator but not definitive proof on their own (as gold-plated items can carry genuine stamps), all items are organized openly on a sorting grid so you can see how each piece is grouped.
18K (750) Gold Jewelry Stamp
Sterling (925) Silver Jewelry Stamp
950 Platinum (PLAT) Jewelry Stamp
Step 3: Diagnostic Karat Validation & Authenticity Testing
To verify exact metal purity without damaging your valuables, we utilize non-destructive diagnostic testing methods right in front of you:
Touchstone Acid Scratch Testing
Analysts gently rub the item across a smooth touchstone, leaving a faint streak of metal on the stone rather than on your jewelry.
- Unstamped Items: Tested using varying acid strengths to establish exact karat purity.
- Stamped Items: Tested directly against acid formulated for its declared karat. If the acid reaction matches our reference baseline, the purity is verified; if the result is borderline, secondary testing is conducted.
Specific Gravity Density Testing
This non-destructive test measures gold purity by comparing an item's mass in air against its displaced volume when submerged in water. Because gold is extremely dense, calculating its specific gravity confirms whether an item is solid gold, thick gold plating, or a base metal alloy.
X-Ray Fluorescence (XRF) Analysis
When visual inspection and scratch testing require further confirmation, we utilize X-ray fluorescence (XRF) testing. This advanced method measures generated X-ray intensities through wavelength dispersion analysis to determine the exact elemental percentage breakdown of all metals present.
Step 4: Precision Gram Weighing & Gemstone Deductions
Once purity is categorized, items are weighed in plain view on certified, calibrated gram scales (recalibration can be demonstrated upon request):
- Gram Scale Accuracy: Items are weighed together by karat category or individually to record net weights.
- Gemstone Weight Deductions: Non-precious inserts and non-diamond-colored gemstones are estimated and deducted from net metal weight (e.g., a 1-carat gemstone weighs approximately 0.2 grams, so four small stones subtract about 0.08 grams).
- The Diamond Protection Rule: Unlike traditional buyers, we do not deduct the weight of natural diamonds if your piece qualifies for our Premium Jewelry pricing.
Step 5: Transparent Quoting & On-the-Spot Payouts
- Live Market Offer: Your payout quote is calculated directly from live spot market rates based on verified purity and exact gram weight. We provide a clear upfront estimate with zero obligation or pressure to sell.
- Immediate Payment: All testing and appraisals are 100% free. If you choose to accept our offer, payout is issued immediately on the spot by cash or business check.
- No-Pressure Service: You are always welcome to compare our written quotes against other local gold buyers. We are confident you will find Portland Gold Exchange to be among the most transparent, honest, and competitive precious metal buyers in Oregon.