I have had this pair of navy suede tassel loafers from Suitsupply for over a year and I love them dearly. However, I have not worn them in almost half a year because the sole was way too light of a brown and created too much contrast with the upper (see to the left). This made the shoes often difficult to wear and particularly hard to pair with a suit. I knew this when I bought the shoes and had planned on darkening the sole since I acquired them. Luckily Andrew Wrigley was nice enough to offer his services. So after a year of procrastination and delay the shoes have reached their full glory!
The procedure is quite simple. I guess the process is something along the lines of some type of shoe repair and how to dye your shoe soles. First, the outside edge of the sole is lightly sanded (1st photo), this allows the leather of the welt and sole to better absorb the dye. Next, the leather dye is applied only to the outside edge and top of the welt and sole (2nd photo). That is followed by rubbing the dye in with a wood block (3rd photo). The final step (not pictured) is to apply a thin coat of wax polish to the dyed areas, this will help restore some of the shine to the sole and welt. Although Andrew is experienced in making shoes I think this is a simple enough operation that it could be carried out by someone with little to no experience in shoe repair. Just make sure you have the right tools on hand and that you practice on something with the brush and dye to familiarize yourself with those things (the dye will stain anything it touches so keep that in mind!). Or you could just take the shoes to your local cobbler or perhaps even the shoe shine stand.
The resulting shoe, in my opinion, is a much more wearable and elegant shoe. A shoe that has now been added to the regular rotation. Victory.