The above illustrations depict the Robertson Red tartan and the Robertson Hunting tartan. There are a few other variations in differing shades depending on whether it is considered ancient or modern. The ancient colors are lighter and not as bright due to the old type dyes that were used.
The wearing of a tartan or plaid goes back to ancient times. The original was called the belted plaid and consisted of one piece of cloth about six feet long. It was draped about the waist and over the shoulder and was held in place with a belt. The plaid itself depended on the area where it was woven and was not necessarily associated with a particular clan.
The modern kilt came into being in the eighteen hundreds. It was more convenient to wear than the belted plaid, and about this same time specific plaids began to be associated with certain clans.
If you want more extensive information on the Clan tartans, as well as more examples, check the Clan Society Web site.