Cirth runes are the creation from the imagination of J.R.R. Tolkien. Tolkien created many languages throughout his life who wrote in one of his letters that the tales of Middle-earth (The Hobbit, The Lord of the Rings and The Silmarilion) grew from these languages, rather than the languages being created for use in the stories. Tolkien also created a number of different alphabet to write his languages - he modelled Cirth on Anglo-Saxon and Norse Runes. Its function in his stories is for inscriptions in wood and stone, just as Runes were used in the real world.
One final thought, The word rune (Old English run) is not merely a form or writing but stirs the imagination and conjures up many possible attributes to it, such senses as 'whisper'; 'mystery'; and 'secret', suggesting that the symbols were originally used for magical or mystical rituals. Anyone who actually understands historical linguistics will realise that it is fundamentally unshaken and that it has cultural implications, even if the age has long since gone when we could envisage Indo European warriors sweeping away earlier populations by force of arms. This is very much the case where history is determined by the victorious in battle? The real knowledge of runes it seems lies logically with the warrior classes or at least by those who are capable of surviving conflict?
Celtic runes are a neo-pagan modern terminology for the Irish Ogham alphabet. Ogham is thought to be named after the Irish god Ogma. One theory of its origins is that it evolved out of a system of tallies used for accounting. Ogham is also known as or ogham craobh, beth luis fearn or beth luis nion. As you can plainly see, the Ogham is not a runic system per se.
Runic Rosary/Heathen Prayer Beads?
Arguments have been posted on the internet suggesting the existence or possibility of a heathen "runic rosary" more popular coined by neo-pagans as "Brisingamen Beads"? I am of the opinion that due to a lack of any archaeological evidence, this is just a personal gnosis. I am not saying that heathens did not pray, just not ancient Germanics with runic rosaries and in this manner. Heathens did indeed pray as suggested by the Second Merseburg Charm. This charm in Old High German which dates from around 750 CE and runs as follows:
1. Once the Idisi set forth, to this place and that;
Some fastened fetters; some hindered the horde,
Some loosed the bonds from the brave --
Leap forth from the fetters! Escape from the foes!
2. Phol and Wodan rode into the woods,
There Balder's foal sprained its foot.
It was charmed by Sinthgunt, her sister Sunna;
It was charmed by Frija, her sister Volla;
It was charmed by Wodan, as he well knew how:
Bone-sprain, like blood-sprain,
Bone to bone; blood to blood;
Limb to limb -- like they were glued.
Ref: Merseburg Incantations (Merseburger Zaubersprüche)
This charm is amazingly similar to the Christianized charms used in the magical healing traditions of German speaking regions, which persists to this day as the Pow Wow healing magic of the Pennsylvania Dutch country. Such charms are not made up on the spot: an old charm, passed down through the generations, is considered most powerful.