whichever color you stain them.

1) "A vacuole is a membrane-bound organelle which is present in most eukaryotic cells. Vacuoles are essentially enclosed compartments which are filled with fluid such as water or various enzymes, though in certain cases they may contain solids which have been engulfed. The majority of vacuoles are formed through the fusion of multiple membrane vesicles. The organelle has no basic shape or size, instead varying its structure according to the needs of the cell." Source and further information: http://en.wikipedia.org/wiki/Vacuole "a fluid-filled cavity within the cytoplasm of a cell, surrounded by a membrane that usually encloses food, water, or air Etymology: Fr < L vacuus, empty" Source and further information: http://www.yourdictionary.com/vacuole "Vacuole Vac"u*ole, n. [L. vacuus empty: cf. F. vacuole.] (Biol.) A small air cell, or globular space, in the interior of organic cells, either containing air, or a pellucid watery liquid, or some special chemical secretions of the cell protoplasm." Source and further information: http://dictionary.die.net/vacuole 2) My understanding is that the vacuole membrane itself is just similar to the cell membrane, mostly transparent, and that the colors come from the pigments contained inside the vacuole. Actually, the vacuole is not to be seen as an "object", but rather as a *cavity*. For observation purpose, cells are often colored or displayed under filtered light. 3) "In many cases, flower and leaf colors are caused by the colored content of the vacuole. The color of the vacuole and that of the plastids may lead to a mixed color. The leaves of the copper beech, where the vacuole's content is red and that of the chloroplasts is green are a typical example. The plastids of the red and brown algae are traditionally counted among the chromoplasts although they contain chlorophyll. The green colour is concealed by the red phycoerythrin (Rhodophyceae) or the brown fucoxanthin (Phaeophyta)." Source and further information: http://www.biologie.uni-hamburg.de/b-online/e04/04a.htm 4) "Cells in upper and lower epidermis were categorized by their vacuole color. Blue and red individuals had mostly blue and red cells, respectively. Lilac and violet individuals had blue and bicolored (red and blue) cells on both surfaces, and red cells on the lower epidermis only. Violet individuals had more blue cells on the upper epidermis than lilac individuals." Source and further information: http://cat.inist.fr/?aModele=afficheN&cpsidt=18700266 "The most complex vacuoles are found in plants. Some contain hydrolytic enzymes and store ions similar to those found in lysosomes, whereas others serve a role in storing pigments which impart color to flowers to attract pollinators." Source and further information: http://www.answers.com/topic/vacuole-1 Further information: "vacuole color palettes" http://www.colorhunter.com/tag/vacuole/1

A vacoule is an empty space in the cytoplasm, a membrane enclosed sac, that is filled with water and various solutes. Since it's an empty space, it has no color.