Updated: Nov 18, 2019
Admittedly, the new classic Wine Grapes, delineates each of 1,368 grape vine varieties as producing one of five idealized berry colors, but I'd be surprised if it displaces common parlance of grapes being either black or white and wine as being either red, white, or pink. Although not widely popular there is also orange wine that looks like some pink wines but is made from white grapes instead of black grapes.
Grape varieties with green, gold, pink, and sometimes darker mature berry skin colors may be referred to as white grapes (Portugal's vinho verde translates as green wine). Many may be using the phrase "white grapes" as shorthand for "grapes used to produce white wine" and that would explain why pink grapes like Gewürztraminer and those with even darker hues like Pinot Gris are also referred to as white grapes. Yet white grapes are also blended to make red wine; for example, when the Chianti DOC was created in 1967, the fermentation had to include from 10% to 30% of the white grapes Malvasia and Trebbiano (relaxed when Chianti became a DOCG in 1984).
It makes sense that "black grapes" are referred to as "red grapes" when attributed the color of wine often made from their juice. Yet Pinot Noir and Pinot Muenier, both approximately the darkest skin color, are often used to make white sparkling wine. In fact, making white sparkling wine without juice from any white grape varieties is enshrined as "Blanc de Noirs".
Of course, white wine is never white, rather it is clear with green or golden hues. Many readers will cringe when I say wine is pink, even though it describes the color well, because of conditioning to say the French word rosé, but are willing to desecrate wine from Bourgogne as being from Burgundy. I don't know why that is the only wine-producing region in France that we use English for.
So what are we to surmise from this state of affairs? Students of wine and industry participants understand the terminology and aren't willing to raise a ruckus to sort it out. Marketers are happy to switch between colors when describing their grapes and wine without worrying about what must surely be silent confusion among their customers, if they even recognize color as a source of confusion at all. Perhaps people working in technical professions have an aversion to ambiguity when there is no need for ambiguity. I simply find it annoying that an industry as established as this one is happy to make well understood words a jargon, encouraging disparagement of wine connoisseurs as elitists.
I won't hold my breath waiting for the industry to use terminology consistently and provide consumers with a glossary. There are simply too many more important collective issues. However, it seems a simple thing for producers seeking a comparative advantage to help their customer base be more comfortable discussing wine. Why not encourage people to participate in the wine culture rather than shutting them down by way of embarrassment?
Three simple statements are all a producer needs to help the consumer of their product:
Grape berries have many colors and they are rarely uniform.
Wine is made from grape juice, which is usually clear, regardless of the berry color.
The winemaker decides what style and color to make the wine.
Examples from a particular producer's product range will clarify the situation nicely.
Engaging customers to think about berry and wine color can boost enthusiasm for and sales of wine, particularly with inquisitive and "promiscuous" wine consumers. Perhaps make a game of naming white grapes in red wines, black grapes in white wines, or the many but uncommon grape varieties that don't have clear juice.
The grape varieties with red flesh (known as "teinturier") or pink juice (Montepulciano) will surprise many enthusiasts. Even wine experts will be hard pressed to name more than a few such grapes. Here are more than two dozen to hold in your marketing "toolkit":
Alicante Bouschet (aka Garnacha Tintorera)
Gamay teinturier de Bouze
Grand Noir de la Calmette (aka Galicia and Alentejo)
Seibel 8357 (aka Colobel)
Vitis amurensis grapes