No, any color may be opaque, even white. Opaque is simply the quality of not being transparent or translucent.
It is Opaque letting no light through.
Aluminum foil is opaque.
Opaque
It is opaque
There are many objects that no light can pass through, although of course, it depends on what type of light you're talking about. The name of the type of object that visible light cannot pass through is called opaque.
Then, your diamond looks opaque white under a black light.
Opaque?
'Opaque' means that light cannot pass through. A mirror or a black body can be referred as opaque objects. But colliqualy the term 'Opaque' is used often as a synonym for 'Opacity'. So 'opaque' can be called a measure of transparency/opacity
Gluesticks are an opaque white.
black paint.
Depending on the particular material and thickness, roller blinds are either translucent (can see shapes through them) or opaque (black-out blinds).
Black and white - no transparency.
Be careful not to confuse: Opaque objects are those that do not allow light to pass through it, but they can reflect light. It is BLACK objects that absorb all the incident light on it. To conclude, opaque objects do not necessarily absorb all the incident light on them but black objects ABSORB all the incident light on them (and are, of course, opaque)
'Good' is a judgement call, and you are the judge.
black as pitch; impossible to see through
White Light
Typically an opaque green, greenish-brown, brown or black color.