Identify the series first
A gold chart can represent spot observations, a reference benchmark, or daily and monthly averages. These are different series. Before interpreting the shape, identify its currency, weight unit, metal and time range, and keep those choices consistent in comparisons.
Calculate from known endpoints
Absolute change is the final value minus the starting value. Percentage change divides that difference by the starting value and multiplies by 100. In an illustrative series from 100 to 105, the change is 5 units or 5%. A move back from 105 to 100 is approximately −4.76%, because the starting point has changed.
Do not compare a short-window change with a full month's performance. A displayed high or low may be the highest or lowest available sample, rather than every movement that occurred between observations.
Check time and conversion method
Look at the final observation's timestamp and the gaps between points. A line that ends before the present, or has a gap, does not demonstrate that the market stopped moving. New data may simply be unavailable. Check the source status instead of inventing missing moves.
In a chart converted into another currency, exchange-rate changes can also matter. Applying today's FX rate to an entire price series produces a reference conversion, not historical local-currency quotes. Read the methodology and do not treat a past pattern as a forecast of the next move.