Red Wines vary in colour from dark pink to almost black. Their colour depends on the grape varieties used, the vintage characteristics, the health of the grapes, the wine methods and the amount of time the wine has spent in tank, barrel or bottle. Red wines are produced in virtually all of the world's wine regions, although the proportion of red wines produced at the cool climate limit of wine production is low, since it can be difficult to develop sufficient pigmentation of most grapes' skins to produce a proper red wine.