Not at all, colour, aroma, and taste are key determinants of quality, and this can vary widely from one Matcha to another. These factors can be assessed in Tencha (dried tea leaves ready to be ground) form.
The best quality Matcha powder will be a vibrant emerald green with a lustrous quality. If the powder has a slight yellow tone, it is of a slightly lower grade. A whitish tone is still lower, while brownish toned matcha powder can be considered very low grade or old. The powder should have a grassy, seaweed-like aroma and a sweet after taste (“umami”) from its amino acids. An astringent or bitter aroma and a biting taste indicate Matcha of lower grades.
In its liquid form, Matcha should also have a vibrant green colour (not yellowish or dull), and a smooth sweet after taste.