It's one of the signatures of the show, linking the cast of Scottish characters to their original timeline and lives in Scotland.
But how true to real life are the tartans used by the clansmen and woman on Outlander?
We know that two main clans feature, that of Fraser and MacKenzie, with both parties involved in the Jacobite rising of 1745 that features prominently in the first three seasons.
With Diana Gabaldon, a sticker for research and ensuring her universe is firmly bedded in reality, and top names like showrunner Ronald D. Moore and costume designer Terry Dresbach keen to ensure authenticity, how did the crew go about working with the fabrics that would feature in the show.
Outlander Tartan
The tartan used in the show is muted and features only flashes of colour for the two clans.
The kilt that Jamie wears isn't the same as the official versions registered for either clan.
Speaking to Elle.com, Terry Dresbach revealed that they wanted to tread the line of dealing with the romantic version of the past and what researchers believe to be the truth.
She said: "What I did was I tried to put myself in the head of somebody in the 18th century.
"So if I'm a weaver or a dyer or a fabric maker and I'm living in a little smoky hovel with three generations and maybe cow and pig in the corner, and it's pouring rain outside all the time, how much time am I spending with that giant pot over the fireplace [dyeing fabric] getting the exact correct shade of lavender? Probably not a lot."
Instead of the bright hues of modern tartans with dyes that would have been incredibly expensive in those days, the experienced designer explained that it was more likely, historically, that these fabrics were created from the environment people live in.
The result was the 'Outlander tartan' which features muted brown and blue-grey blocks and stripes, with two variants, one for the Frasers – with fine yellow and red stripes – and one for the Mackenzies – with additional light blue stripes.
Clan MacKenzie Tartan
The real Clan Mackenzie tartan according to the official Scottish Register of Tartans is a much brighter affair with squares of a sea blue and vibrant green intersected by thin lines of red and white.
The Mackenzie is the regimental tartan of the Seaforth Highlanders, who were raised by MacKenzie, Earl of Seaforth, in 1778.
Clan Fraser (of Lovat) Tartan
Though there are variances, with modern, ancient, dress and hunting versions of each tartan, the Fraser of Lovat tartan registered with the TRST features bright squares of red, blue and green.
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