Because one PAXG is always redeemable for one ounce of vaulted gold, its market price is tethered to XAU spot by arbitrage rather than by decree. The gauge makes that tether visible: needle at centre means Binance PAXGUSDT and the spot reference agree; drift to the right is a premium, drift to the left a discount. Shading around the middle covers the ±0.3% window where the spread usually stays, and the colour strengthens outward from there because both far ends are anomalies for a redeemable claim on metal rather than a verdict on the trade. Figures are shown in both dollars and percent and clamped at ±1% so ordinary moves stay readable.
The interesting information is in persistence, not in single ticks. Premiums that refuse to fade suggest on-chain demand is outrunning fresh issuance from Paxos. Discounts rarely last, and the reason is mechanical: anyone can buy discounted tokens and turn them back into bullion, unallocated Loco London gold, or dollars at par through the Paxos platform, so the deeper the discount, the stronger the force closing it. Each of those terms has a plain-English entry in the gold market glossary.