A word of advice, if you buy a German helmet from an on-line auction, be very careful and ask the right questions. If the seller sends you fuzzy pictures or seems apprehensive to answer questions, do not bid. A very high percentage of German helmets listed at on-line auctions are fakes or have at least been tampered with. Most likely the number of non-original helmets approaches 95% or more. You can get lucky and find good German helmets at an on-line auction. Collectors usually know the good ones when they come up and they usually they command a high price. On the flip side, if a deal seems to good to be true, then most likely you are dealing with a reproduction. Stay away from helmets outside the US. Virtually all have been tampered with in some way. Ebay is a very dangerous place to buy German helmets. It has become a dumping ground for the post war fabricated pieces. There are also several Ebay sellers in the US acting as fronts for various East European fakers. They all have the same story, such as direct from a Vet estate, or a small museum. The best way to have a high quality collection is to buy your WW II German Helmets from reputable dealers, that offer an inspection period and stand behind the product with a Lifetime Guarantee.
The first introduction of drab general uniform was by the British Corps of Guides in India in 1848.  Initially the drab uniform was specially imported from England, with one of the reasons being to "make them invisible in a land of dust".  However, when a larger quantity was required the army improvised, using a local dye to produce uniform locally. This type of drab uniform soon became known as khaki ( Urdu for dusty, soil-coloured) by the Indian soldiers, and was of a similar colour to a local dress of cotton coloured with the mazari palm .  The example was followed by other British units during the mutiny of 1857 , dying their white drill uniforms to inconspicuous tones with mud, tea, coffee or coloured inks. The resulting hue varied from dark or slate grey through light brown to off-white , or sometimes even lavender . This improvised measure gradually became widespread among the troops stationed in India and North-West Frontier , and sometimes among the troops campaigning on the African continent.