You've moved past the 'bright green = good' stage. Now you're hunting for nuance: the difference between a spring harvest and a fall harvest, the impact of stone grinding vs. blade grinding, and why the color of the froth matters more than the powder.

For you, color is still a shortcut to freshness. A dull yellow-green powder tells you the matcha is past its prime, even if the package says 'high grade.' Oxidation happens fast once the tin is opened. That's why you should buy smaller tins and use them within a month.

Also, pay attention to the froth. When you whisk, you want a thick, creamy foam. If it's watery and thin, the matcha is likely stale or low-quality, regardless of the powder's hue.