Do modern lab tools prevent blood's exposure to oxygen

Inside our bodies, blood is more of a dark purple-ish color; It's the exposure to oxygen that makes it look red when we get cut, right?

But I've noticed that when I give a blood test, the blood looks rather dark as it's being collected into the clear vials. It still has a hint of red, but it's much much darker than it is when I've cut myself and collected it on a towel. Does it just appear darker because there's so much in the vial, or has it actually been unexposed to oxygen and still the same color as it was inside me?

Does exposure to oxygen effect it in any other way besides color? For example, if I were to prick myself, and collect the blood sample by just letting it drip into the vial rather than having it collected through the tube...would test results be inaccurate since it was exposed to more oxygen? (Granted, of course, that it hasn't been contaminated by something else during the trip from my arm to the lab)

"Inside our bodies, blood is more of a dark purple-ish color; It's the exposure to oxygen that makes it look red when we get cut, right?"
Wrong. Blood is always red due to the hemoglobin, which is the substance that is inside the erythrocytes and the one that carries the oxygen from the lungs to every cell in the body.
Blood that is oxygenated looks more red that blood that is not oxygenated. But they are both red.

"But I've noticed that when I give a blood test, the blood looks rather dark as it's being collected into the clear vials. It still has a hint of red, but it's much much darker than it is when I've cut myself and collected it on a towel."
This is because when you are given a blood test, they always take the blood from a vein, which is the conduct for no-oxygenated blood - the one that appears more blueish. The blood that is oxygenated goes through arteries, but you never get a blood sample from an artery - unless that is a special test designed to measure your blood pH, and the oxygen and CO2 level on it.