Vass wingtip bluchers in Color #8 shell cordovan with double leather soles (Budapester model, Peter last). These shoes spent a couple of years as samples for Gabor Halmos, the Vass US representative, so they've acquired some of the patina that shell cordovan is known for. It's not a patina, really. It's a gradual wearing-off of the color that the shell cordovan is dyed. Shell cordovan is not an animal hide; rather, it is a subcutaneous membrane around the rumps of horses. Its fibers are very dense and don't take the dye very well, and this natural resistance to dye is accentuated by the fact that it undergoes vegetable tanning. It's simply impossible to obtain the depth or saturation of color that one finds in chrome-tanned leather with vegetable tanning. The result of all of this is that shell cordovan tends to lose color with age, although not uniformly. Heel counters, toes, and crease lines will lose color more rapidly, giving the shoes a sort of reverse-antiqued look.
It's worth noting that Alden redyes their Color #8 shell cordovan to give it a deeper burgundy color. Other makers, including Vass, do not do this, the result being that Alden Color #8 shoes are always darker than those from any other maker.