This is taken from the story of Féidlim Tonn Rí 's Castle and it's a 'formula' that is repeated quite often as the story unfolds, so I'm guessing that those who would be listening to it would probably join in in saying it. It's a description of Féidlim Tonn Rí 's Daughter.

'because she had hair as black as the Raven's wing,
skin as pure as the snow on the ground,
cheeks like mixed snow and the Raven's blood,
and lips like the blood itself.

'mar go do bhí gruaige (chomh?) ciardhubh chomh le sciathán an Fiaigh Duibh,
craiceann chomh glan (gléigeal?) le sneachta ar talamh,
gruanna chomh le sneachta measchta le fuil an Fiaigh Duibh,
agus liopaí chomh dearg le fuil féin aici.

I'd be glad of any improvements and corrections you might have.
Franc

I'd read it as skin as white as snow.... and cheeks like snow mixed with raven's blood

Ah well, it's the English I'm trying to put into Irish, not the other way round - it must have been in Irish at one time, but here I've transcribed the words as they're spoken in English.

Perhaps:

'mar go raibh ceann gruaige uirthi chomh ciardhubh le sciathán an Fhiaigh Dhuibh,
craiceann chomh híon le sneachta ar talamh (or leis an sneachta ar an talamh),
gruanna mar shneachta measctha le fuil an Fhiaigh Dhuibh, (or mar shneachta agus fuil an Fhiaigh Dhuibh measctha le chéile)
agus béal mar fhuil féin.

or you could try connecting the different attributes with a "her":

'mar go raibh a cuid gruaige chomh ciardhubh le sciathán an Fhiaigh Dhuibh,
a craiceann chomh híon le sneachta ar talamh,
a cuid gruanna mar shneachta measctha le fuil an Fhiaigh Dhuibh,
agus a béal mar fhuil féin.

Await correction or confirmation ...

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[hr]Múinteoir Gaeilge - Irish Teacher[/hr]
My "specialty" is Connemara Irish, particularly Cois Fhairrge dialect, but I can also speak Ulster and Munster Irish with native-level pronunciation.
Is fearr Gaeilge ḃriste ná Béarla cliste, cinnte, aċ i ḃfad níos fearr aríst í Gaeilge ḃinn ḃeo na nGaeltaċtaí.
Gaeilge Chonnacht (GC), go háraid Gaeilge Chois Fhairrge (GCF), Gaeilic Uladh (GU), Gaelainn na Mumhan (GM), agus Gaeilge an Chaighdeáin Oifigiúil (CO).

Go raibh maith agat.
Would it more usual to say 'mouth' rather than 'lips' when describing a lady's red lips ?

I think béal sounds more poetic in Irish - but that could just be me ...

_________________
[hr]Múinteoir Gaeilge - Irish Teacher[/hr]
My "specialty" is Connemara Irish, particularly Cois Fhairrge dialect, but I can also speak Ulster and Munster Irish with native-level pronunciation.
Is fearr Gaeilge ḃriste ná Béarla cliste, cinnte, aċ i ḃfad níos fearr aríst í Gaeilge ḃinn ḃeo na nGaeltaċtaí.
Gaeilge Chonnacht (GC), go háraid Gaeilge Chois Fhairrge (GCF), Gaeilic Uladh (GU), Gaelainn na Mumhan (GM), agus Gaeilge an Chaighdeáin Oifigiúil (CO).

Ceart go leor

I should also point out that béal also means "lip":

béal uachtair "upper lip"
béal íochtair "lower lip"

_________________
[hr]Múinteoir Gaeilge - Irish Teacher[/hr]
My "specialty" is Connemara Irish, particularly Cois Fhairrge dialect, but I can also speak Ulster and Munster Irish with native-level pronunciation.
Is fearr Gaeilge ḃriste ná Béarla cliste, cinnte, aċ i ḃfad níos fearr aríst í Gaeilge ḃinn ḃeo na nGaeltaċtaí.
Gaeilge Chonnacht (GC), go háraid Gaeilge Chois Fhairrge (GCF), Gaeilic Uladh (GU), Gaelainn na Mumhan (GM), agus Gaeilge an Chaighdeáin Oifigiúil (CO).

Here's some more - I'm not sure about this either.

"Ah" says the Raven "that's all very fine
but I'm now putting you under geasa
to go travelling
and not to sleep the second night in any one house
or to eat the second meal off any one table
and to find Féidlim Tonn Rí 's Castle
within a year and a day
or misfortune will befall you."

"Á" arsa an Fiach Dubh (I'm not sure whether in Irish it's better to tell the story in the past tense or the present) "tá an uile go hana-bhreá sin
ach mise anois, táim ag chur fé gheasa agat
go n-imí tú ag taistil
agus gan an dara oíche do codladh san aon tigh amháin
nó gan an dara bhéile do ithe ar aon bord amháin
agus go (the verb I would like to use here is aimsigh, but I'm not sure if it should in the subjunctive or not) an Caisleán Fhéidlim Thonn Rhí
nó tiocfar an drochrud ort"