A gythia is the female version of a gothi, that is, a priestess and a priest.
There isn't really such a thing as ritual garb for us, but many feel more comfortable performing rituals in Norse type clothing. Then you'd wear whatever is the fanciest "viking style" garb you can muster up, I guess. Most people would just show up wearing their regular clothes, I guess. I know my gythia has spent a lot of time researching what a seith kona would have worn (as she is both gyhia and seithkona - both titles apply to her, so she can really dress as either), and sometimes she wears things similar to that when she performs rituals. That has nothing to do with playing dress-up or whatever, but it is something some people do to pay respect to their ancestors. Sometimes I think it also makes you feel closer to the gods and godesses, because when we think of them, we think of them in that shape (the formidable Norseman or Norsewoman, you know? As for myself, I have not seen any of them like that - Odin, for example, has only ever come to me as a large , black wolf, Ran as water, Loki and Frey only as faces etc. Well, no, that's not true! Thor was a whole person once, but I don't remember what he was wearing...).
Thinking about this, I now realize that I myself have not worn garb to a ritual for years and years, but then again, when I
do don garb for other events, like demos at schools, public events or fight practise etc to do with Norse history, it does remind me where I come from and how I was shaped through my cultural heritage. I suppose that can make you feel closer to whomever you worship.
As to your question itself, I know that a seith kona's garb is very specific as it is so carefully described in the lore. Every detail is important and I have not researched it very well, and so cannot do it justice here. so I will not speak to it. I can most certainly find out for you from my gythia, if you want. When she dresses as a gythia for ritual, she wears a floor-length trimmed tunic, sometimes with an apron dress with Norse-style brooches, a belt and the apropriate bling bling. If it's cold, there's a cloak and cloak pin. I have seen her garb often enough to know the colours and textures etc by now (I've even help make some of it). Actually, here: (pics from an Althing I did not attend, but that at least has some pics of Susan in garb - wish I couyld figure out how to upload pic onto this thing, cuz I actually have close-up pics on myself and my whole family in proper garb...)
http://images.google.ca/imgres?imgu...=/images?q=susan+granquist&svnum=10&hl=en&lr=
Susan is the woman in the blue outfit, top pic on right. My gothi would wear the baggy Rus style pants with leg bindings, a red, trimmed tunic, bling bling, a wide belt with the required scrama seax attached, and, if it's cold, a cloak with cloak pin. My gothi takes pride in doing his very long hair and beard before a ceremony. Both may have some sort of binding, braiding or whatever in it.
As for myself,
if I were to wear garb, it'd be the typical white creased underdress, a dusty rose or blue tunic, a linnen apron dress with large brooches a hand-wowen belt with my keys, sewing kit, knife and other women's gear attached to it, amber and silver bling bling galore ( I
am Norse, you know...), and I would probably do my hair up in a braid or a bun or something.