Cloak of Invisibility was actually not invented by J.K Rowling , for it appears in folklore that is certainly older that Harry Potter franchise, sorry fans O.o
The cloak appears in “The Twelve dancing Princesses” ( originally ” The Worn out dancing shoes” ) a fairytale by Brothers Grimm , and in some Scottish folklore as well. This interesting fairytale can be read here
In the ever so popular trilogy, Lord of the rings, Frodo Baggins is the "bearer" of magickal ring that among other, enables bearer to render onself virtualy invisible. Simmilar ring , according to occult tradition ( and instructions of certain Hebrew alchemist ) had to be created from electrum, in specific date, and the n inscribed with Divine name/s and carried on indicated finger to attain real-deal invisibility.
In magick and occultism , attaining virtual or “practical” invisibility was ( thankfully ) a subject treated with respect and care, which resulted in abundance of magickal techniques fo r attaining the same . From potions to Higher magick spirit invocations, many such methods survived , and are still used today. Some can seem downright simple, as simple as carrying a plant or stone in proper manner, but are very effective , powerful nevertheless. For the key is in knowledge how to employ something, with intention, in proper magickal manner ;) Creole people have a nice saying regarding that : “nothin’ can be ‘da conjure, and anythin’ can be ‘da conjure’”
But the question remains, being a subject of debate of occult scholars and those aspiring to such, werther or not, the actual invisibility ( the “real deal”, transparence etc ) is possible. I personally do not doubt it for a moment, to be possible. First off, many supernatural entities are very capable to being invisible. Whatmore, they spend most of their time being unseen. And I also believe that humans can become invisible, even by will. Such operation success though most often depends on difficult ceremonies and hard to attain, rare tools or charms. It has actually to do with devotion, for If You want to do wondrous things using magick, like with everyting else in life, You’ll either have to be insanely lucky, or You’ll need to pull up Your sleeves and do some hard work. Most modern spells and spiritual techniques offer practitioner what seems to be , a form of glamour, which makes one unnoticeable to others , and as long as attention is not ( intentionally ) drawn to oneself, one is simply not perceived by other human beings, despite being physically there, having a shadow and mirror reflection. To me it’s more than acceptable, for If You are to go about it wisely , the only person noticing that You are not actually transparent shall be You , yourself. The result will be same nevertheless. If You however want to scare people by making them see floating cigarette You hold in hand, You’ll have to try very hard, indeed, show determination, devotion and lots of effort . Sometimes even sacrifice something. But enough with that, let’s move on practical part ;)
Magickal invisibility timing
Saturday and Monday , and hours of Saturn and Moon may be most beneficial for such work. But the holiday which was always tightly correlated to invisibility is Midsummer, Summer Solstice or the Feast of St. John’s birth ( 24th of June ) , when Fern seeds are traditionally gathered for various magickal uses. Chicory root is also plucked , in a specific manner on this day to attain invisibility. Solomonic traditions associate Capricorn time with Invisibility. Traditionally for such “magckal operations”, certain parts of the day, namely twilight and midnight ( sometimes also dawning ), are most favorable.
Simple charms with herbs and stonesn for invisibility
Let’s go through few illustrative examples of simple, yet powerful charms that enable one wide range of effect, from simple less noticeable appearance, or less attention drawing to virtual invisibility, as folklore suggests : • According to Albertus Magnus , carrying and Opal wrapped in Bay Laurel leafs should provide invisibility or at least unsociability to the bearer of the charm • Similarly, Heliotrope stone, carried wrapped in Heliotrope leaves or dressed with Heliotrope oil should so the same 
• Wreath of Amaranth flowers worn as Crown, particularly when collected in certain times of power and enchanted properly is amazingly powerful invisibility tool that can make one virtually unnoticeable
• Seeds of Ferns, carefully gathered around Midnight on Night of St. John, then carried in pouch bag or sprinkled in Your path are said to confer invisibility to the user
• Similarly Hellebore ( Christmas rose ) collected and dried with intention ( flowers and leafs ) sprinkled before one, as one walks, shall enable one to go around completely unnoticed as long as one does not draw attention
Several books on magick, particularly those dealing with magickal herbalism , speak of potion made of poppy seeds soaked in red wine for 15 days. Such potion is later ingested, to become invisible by will. None of the sources is clear though on whether or not the potion’s effect is reversible, and how it’s actually used/ingested ( ??? ) . Judika Illes in one of her works suggests drinking it for five consecutive nights. Other sources I’ve consulted, however, make no reference of such ( “application method” ) or perhaps the preferable time for making such potion. Since such potion is to essentially “reduce” someone’s visibility, I suggest soaking the seeds in vine during the descent (waning) of the Moon.
The notorious black cat bone
Although the usage, and folkloric methods of attaining the miracleous black cat’s bone, had been popularized and dealt with in terms of Hoodoo and Conjure, I can assure You it might not be indigenous to such ( African-American folklore aimed here, not Hoodoo as a system of magick ). Such bone, was among other uses , employed to become invisible, by placing it in the mouth. It would create actual invisibilit y , then mirror reflection/image disappears, and one can not be seen even if addressing to others of touching them. For I have been taught methods described in folkloric accounts on Hoodoo, long time before I ever heard or read the very word Hoodoo, or even Voodoo. Growing up in Eastern Europe, I was told of ( heck I had been taught ) methods of attaining the black cat’s special bone, which when placed in one’s mouth shall turn one invisible. As a little child, I have had listened of such methods, from cunning old folk, willing to satisfy ever pending curiosity of kid, interested deeply in spiritual and intangible. It’s also present in various European grimoires, so that could be how it “entered” Hoodoo. The same methods applied. The poor animals were supposed to be cooked alive, sometimes with some seeds or tree branches, at midnight , on crossroads , and until the meat would fall of the bones, and that special bone would appear floating, or would be recognized according to instructions ( specific morphologic/ anatomic location, near the scapula, or bone that’s colored differently often black, or by placing each bone one by one in mouth, for testing etc). Hoodoo methods recorded by folklorists such as Zora Neale Hurston or H.M.Hyatt , if differ, differ insignificantly and may simply be local, or even individual ( subjective, informant’s ) variation . Now I have never cooked a living cat, nor , as I believe, would I ever do it, but I decided to discuss the method in this post here, for it’s folkloric and educational value. And If You’d like to read more on it , I warmly suggest following webpage: http://www.luckymojo.com/blackcat.html
Higher magick methods
Many “politically correct” Neo Age practitioners, may describe attaining invisibility via magickal mean, as earthbound , profane, downright practical and shallow. If we look on it from such perspective, invisibility has really no place in Higher magick ( Ceremonial magick, Solomonic magick etc ) which ever deals with invocations, evocations and honors elevated aims and spiritually uplifting aspirations. Well , the higher magick offers some of the most elaborate and effective methods for attaining invisibility, and as one author stated “favored by royal spies…” 
among which are some of the “forefathers” of modern Ceremonial magick. Anyhow, here is the example from “Clavicula Solomonis” often used to illustrate image magick as well:
“Make a small image of yellow wax, in the form of a man, in the month January and in the day and hour of Saturn, and at that time write with a needle above the crown of its head and upon its skull which thou shalt have adroitly raised, the character following. ( see Figure5. ) After which thou shalt replace the skull in proper position. Thou shalt then write upon a small strip of the skin of a frog or toad which thou shalt have killed, the following words and characters. (See Figure 6.) Thou shalt then go and suspend the said figure by one of thy hairs from the vault of a cavern at the hour of midnight, and perfuming it with the proper incense thou shalt say:
-- METATRON, MELEKH, BEROTH, NOTH, VENIBBETH, MACH, and all ye, I conjure thee, O Figure of wax, by the Living God, that by the virtue of these Characters and words, thou render me invisible, wherever I may bear thee with me. Amen. And after having censed it anew, thou shalt bury it in the same place in a small deal box, and every time that thou wishest to pass or enter into any place without being seen, thou shalt say these words, bearing the aforesaid figure in thy left pocket: -- Come unto me and never quit me whithersoever I shall go. Afterwards thou shalt take it carefully back unto the before-mentioned place and cover it with earth until thou shalt need it again.” 
imageanchor="1" style="margin-left:1em; margin-right:1em"> Another,
Higher magick spell, or rather ritual/ceremony, promises no glamour, real invisibility, however requires dead man’s head, and 9 days of devoted watering the same, among others. In the mouth of the head, bean seeds ( beans ) are stored during the whole ceremony, and are upon accomplishment of the same, placed inpractitioner’s mouths to render them invisible ( yuck ! ) We can notice the curious method of deployment of invisibility charm-item once again ( like in the case of black cat bone ) it’s placed in the mouth
“To Make oneself Invisible. Collect seven black beans. Start the rite on a Wednesday, before sunrise. Then take the head of a dead man, and put one of the black beans in his mouth, two in his eyes and two in his ears. Then make upon his head the character of Morail. When you have done this, bury the head, with the face upwards, and for nine days, before sunrise, water it each morning with excellent brandy. On the eighth day you will find the spirit mentioned, who will say to you:
"What wilt thou?"
You will reply: "I am watering my plant."
Then the spirit will say: "Give me the bottle, I desire to water it myself."
In answer, refuse him this, even though he will ask you again. Then he will reach out with his hand, and will display to you that same figure which you have drawn upon the head. Now you can be sure that it is the right spirit, the spirit of the head. There is a danger that another one might try to trick you, which would have evil consequences—and in that case your operation would not succeed. Then you may give him the bottle, and he will water the head and leave. On the next day-- which is the ninth--when you return, you will find the beans that are germinating. Take them and put them in your mouth, and look at yourself in the mirror. If you can see nothing, it is well. Test the others in the same way, either in your own mouth, or in that of a child. Those which do not confer invisibility are to be reburied with the head.” 
Goodl luck If You try becoming invisible Many Blessings , Shadow
NOTES: This article was composed and written by myself, and therfore, should You wish to use it elswhere online, add credits, Shadow of Shadow's magick place, firstname.lastname@example.org or a direct link to this post
CREDI TS AND REFRENCES:
 According to Judika Illes
 Namely : “Magick potion” Gerina Dunwich , “Encyclopedia of magickal herbs” Cunningham Scott
 Aaron Leitch made such reffrence in his "Secrets of grimoire s"
 Quoted from: http://www.sacred-texts.com/grim/kos/kos15.htm , for discussion and explanatory purposes , with no ill will
 Source “Grimoirum Verum” , quoted here for explanatory, discussion and informative purposes, without ill will
IMAGE CREDITS: The first image is from www.artinfo.com and is used here for illustrative purposes without any ill will, and depicts an musician Goty e, in a still from his video "Gotye feat Kimba" Somebody that i used to know"
The symbols are from Clavicula solomonis, found on Sacred tetxs website, as given above, in credits, and is used here in explanator y manner, without any bad intentions