For a woman to train in assessing stains, she has to find a halachic authority to train her and set aside many hours for training. Nishmat Yoatzot Halacha Color that fades - Nishmat Yoatzot Halacha
Some contemporary poskim permit high-quality color printing or apps, provided they are tested against a master original. However, screen variation makes most smartphone-based charts unreliable. Stick to physical strips kept in good condition (not faded). niddah color chart
A critical aspect of the Niddah color chart is the limitation of printed media. For a woman to train in assessing stains,
The Niddah Color Chart is an essential tool in the observance of Family Purity laws, serving as a visual guide to distinguish between prohibited blood colors and permissible discharges. While modern printed charts provide a useful reference, they are not infallible. The complexity of color perception and the severity of the Halachic implications mandate that ambiguous colors be evaluated by a trained Halachic authority rather than relying solely on self-assessment via a chart. Stick to physical strips kept in good condition (not faded)