That uses a verb "is coloured", French could use a verb also. This is not typical French usage either. shirtsn1 is correct Duolingo is teaching "une couleur". http://dictionnaire.reverso.net/anglais-francais/is%20coloured
That's a perfectly natural way to say it in English, if not the most common. They may, ostensibly, have the same meaning, but you version is not the sentence structure Duo wants to teach you. Duo is silly on occasion, but don't chalk everything you don't understand up to that.
When you say something has a white color, it may be some form of white. Yes, Duolingo is teaching "une couleur" and it is a convenient way to make sure you know the feminine version of the color so they repeat this with other colors. It is also more common in French to say "The egg is white.", "L'oeuf est blanc." Also "is colored" is a verb that is also translatable into French "est teinté" or "est coloré", but they are not ready to teach you the Passive verb forms yet.
Adjectives match the gender/number of the noun they describe (except for the exceptions, like 'marron'). So 'blanc' is for a singular, masculine noun (un manteau blanc); 'blanche' is for a singular feminine noun (une jupe blanche); 'blancs' is for a plural, masculine noun (des manteaux blancs); and 'blanches' is for a plural feminine noun (des jupes blanches).
The funny thing is the egg yolk is often reffered to as "le jaune d'oeuf" http://dictionnaire.reverso.net/anglais-francais/yolk
A lot of people complained about this sentence and another that is similar to it. This sentence is not aiming to give you the most common way that this information is often said. This sentence structure is perfectly correct (in both languages). Don't assume that Duo is always going to ask you for the most common speech pattern. If you think a little bit you can come up with at least one scenario where saying this in this way is perfectly normal. [2015/12/19]
Generally speaking, the whole point here on duolingo is to be literal.
Also, some times when a sentence has no context it can seem unnatural, even if it is perfectly acceptable. There are contexts in which this sentence would be normal. There is a difference between, "it is white," and "it has a white colour." Was the egg actually literally white, or was it a type of white? Off-white/winter-white/etc. are all a white colour, meaning they are white with a hint of another colour. In other words, if the conversation is not about a literal white as defined by number on the colour spectrum, but, about a whitish colour, the sentence is natural.
Say you are learning to cook, the colour of things change in regards to the stage they are in. If the teacher is looking for an indication of the colour stage the egg mixture is in the answer could very well be, "the egg has a white colour.' If you climbed a tree and found an egg and you are asking someone on the ground what kind of bird laid the egg, and the person asks if it is closer to the white colour family or the blue colour family rather than argue the vagaries of colour, you would naturally answer, "the egg has a white colour."
You say the shirt is purple and your friend says it is violet, after a heated debate you give up in frustration and say, "it has a purple colour." You could also say, "it has a purple colour to it," "it is purplish," or, "it has a purplish colour," which also express the same thing. Maybe the shirt was in fact a lavender colour. But, then, was it dark lavender, or pale lavender? I don't know what specific lavender it was it was just some type of lavender colour!
I'm not sure that the point is to be literal. I would say that the point is to learn French, and literal and idiomatic understanding of both French and English have an important role. Of course, sometimes a literal translation will be impossible, nonsensical or just unnatural.
In this case, however, I don't believe there is any difference in meaning between "The egg is white." and "The egg has a white color." (Aside from some fairly airy philosophical distinctions between essence and attribute, that is.) Take any of your examples:
If the egg is winter-white, then it is white. Every instance of white is some particular shade of white. The fact that a shade of white has a been named does not mean it is not white.
If the egg is off-white in the sense that it is beige, then the egg is not white. So, in this case, one could just as well say, "No the egg is not white, it has an off-white color." This would mean precisely the same as, "The egg is not white, it is off-white." To be clear, depending on point of view and how far from bright white the shade was, one might also say, "The egg is white, it has an off-white color." Again, this would mean precisely the same as, "The egg is white -- off-white."
Your chef could just as well say, "At this stage, the egg is white." If she means that the egg is kind of white, or a bit less yellow than it was, or not yet black, then she is being just as imprecise in saying that it "has a white color" as she would by saying that it is white.
I think your basic point is that "it has a white color" may be intended to express the idea that an object's color is not truly white, but close to white. But that would be "it has a whitish color." That is not literally what "it has a white color" means.
When I said the point was to be literal, I meant that when you are translating words from one language to another Duolingo expects the most appropriate literal translation (as determined by them at the time, then changed as necessary in response to popular demand). There is no living, or thinking being, responding to your answers with which to discuss how close your translation is to what was given.
The rest of the discussion was in regards to the use of the phrase assuming the individual was not familiar with english and providing an understanding that there were in fact ways that the statement could be used. We could argue for days as to what should or should not be referred to as white, or some other colour, or when something changes from white to being more accurately referred to as beige. Or, the massive number of different ways the same thing could be communicated. However, this was not the purpose of the discussion.
The actual sentence as given has no context, and as such has no meaning; without purpose something vague can have no definitive meaning. You can give it whatever meaning you like and it could be true but what is the point. I responded to dhmorgan001 because I do not believe it is helpful to simply declare a phrase to be unusable simply because they chose to say it some other way and got it wrong, when it is in fact a useable phrase. I gave examples of scenarios in which one may use the words and be understood as being logical.
Saying something has a white colour allows it to fall within a wide range of options in regards to degree of whiteness. To say something is white ignores the options. If there are three objects in a bowl, one is white, one is creamy white, and one is greyish white and I ask you for the white object, are you going to tell me they are all white and get into a discussion about degree of whiteness or are you going to hand me the white one?
I actually hear X is C in color a lot. It matches one of the 6 translations using the U.S. spelling of color for this exercise, and seems merely redundant rather than broken. My guess is that the most natural English The egg is white is not accepted here because the French sentence is also redundant.
Duo marks it as an error if your typo happens to be a valid word. For instance, "while" is a valid word in English and hence your answer was marked wrong. If you had written "whiye" or anything else that isnt a word in English, your answer would have been accepted and you would have escaped with a warning. :)