The color of the brewed tea. The same sencha runs from a clear yellow-green when lightly steamed to a deep, cloudy green when deep-steamed. Cloudiness is not a fault.
In more detail
Liquor color says a lot about the tea's condition. Light-steamed sencha is a clear pale yellow-green; deep-steamed is dark and cloudy; gyokuro is pale but visibly viscous; hojicha is reddish brown. A green tea that pours brown has either been roasted or has oxidized with age — which makes color a useful early warning that a packet has gone over.