Dear Briha,
Here is a quick overview
Making a Japanese blade be it a Katana or any other blade begins with the processing of Iron bearing Sand into "Tamahagane"
The whole smelting process is very unique, and is still carried out in the Tradtional Manner, wherein a Clay Furnace/smelter (also called Tatara) is built and the iron is processed for 3 days.
This process which involves smelting the Iron Sand "Satetsu", which has Iron Ore along with Charcoal, the whole process is unique and requires a delicate balance of temperature, and the amount of Iron Sand and Charcoal which is being used. Its a lengthy process and I will be happy to share videos later. Basically this process creates both High Carbon & Low Carbon steel.
This steel is sorted and crushed into a plate, post this it is crushed again and soft and hard steel is sorted and separated in heating trays. The soft steel called "Shingane" forms the inner core of the sword and the hard steel forms the outer body called "Kawagane"
The next step is to forge the Shingane, the inner core, the heating tray heats the metal to 1300 degrees, where the metal is then forged into a bar, which is horizontal, this bar, is then semi cut, (for the lack of a better word) into half, folded, hammered, folded in half, till the Smith decides that the "Shingane" is ready.
Post this the "Kawagane" starts getting shape in a similar mannner to the above, only in this case the the Folding and Hammering process can vary for 8-16 folds, again depending on the smith.
Once the "Kawagene" horizontal bar is ready, it is then shaped out into a Hollow 3 sided "U" shaped tube, so that the "Shingane" can be inserted into the same. Once the 2 pieces are welded together, the process of making the blade begins. The temperature of the metal at the time of forging is 900-700 degrees approx.
The blade now begins to take shape, at the first stage we get the Blank called "Sunobe" the Sunobe, then using finer tools is cut to provided the desired shape of the blade. The first step is getting the point, so a diagnoal cut is made and the "Kissaki" or point is made as required.
Post this the blade is heated, and the cutting edge is hammered out on the "Kawagane" at roughly 700 degrees, once this is done, the sword which till this time is "straight" and does not carry the curve we are all so aware about in Samurai Swords, the sword is roughly finished using a square file, for which I dont remember the name
If the file does not do the Job a coarse Japanese Whetstone is used sparingly.
It is at the next stage that the blade, transcends to a work of art. The application of the clay is perhaps one of the most delicate tasks, and the results in the eventual pattern of the blade, the clay is mixed with crushed charcoal and whetstone (In what measure, I have still never found out)
Post this the blade is ready for Heating, this is the stage where the True Master smiths emerge, the heating and Quenching called "Yaki-ire" is done mostly at night by master smiths. The reason for this is, that they need to study the colour of the flame! The forge temperatures at the time of the heating is generally at 700 degrees odd, however the master smith is more interested in the colour of the fire and the blade! It is delicate balance and the right time for removing the blade from the forge and tempering it in water "yaki-ire" is a decision the master smith takes, based on a life time of experience. Apprentices can practice for several years, before they can master this part of sword making.
All the effort that has gone in so far in making the blade can be turned to dust, if the blade is not taken out at the right time and tempered.
Once the smith approves the colour, the sword is taken out and plunged into the water for tempering, it is here that the shape of the sword changes from straight to curve. The clay captures the heat and as the soft and hard steel sets at different temperatures, the sword tips slightly down, then up forming the Curve of the sword.
Once the tempered blade is taken out of the water is checked for imperfections, and slight imperfections, are corrected. The smith may or may not give it a rough polish, before sending it out to the Master Polisher.
The thing to understand about making a "Shinken" is that it is truly a collaborative effort between different masters, all well versed in their art.
Once the Blade arrives at the master polisher, he can take several weeks to finish the polish. The work of the Master Polisher is a true work of art, as he is the one who provides the aesthetic finish to the blade, which all "Shinken" are so famous for. He will not only polish the blades, but will hone the blade as well.
Polishing consists of 2 parts, foundation called "Shitagi-togi" and finishing called "Shiage-Togi" . In order to perform "Shitagi-togi" the polisher sits crouched on his knee, and uses the most coarse Japanese Whetstones, to start the foundation, the foundation stones are generally quiet large, but handy, and they prepare the sword for the next stage. This stage requires that they take away just enough steel and not too much, which will affect the finishing.
In the "Shiage-Togi" process, the polisher again changes his stance, and might do so several times during the finishing. Some smith, keep one knee down and one knee up, and the start polishing the stones from back to front. This is done to avoid cutting oneself on the sharp blades, the size of the whetstone keeps going smaller and smaller till at the end, they are mere wafers, which the smith are using to polish using their thumbs and fingers.
It is at this stage also that the Hamon is highlighted, Iron Oxide mixed with "Nugui" Oil is applied to the blade, depending on the type of finish required, such as Aesthetically bright! or a more Matted down finish different combinations of oils are used. The whole polish process is extensive, and complicated, and I cannot hope to capture the magnanimity of the process in a few lines!! So please pardon any slips!!
Post this the blade is sent to the scabbard maker the Saya, Koshiare are added in the process and finally, the Habaki, Tsuba and finally to Tsukamaki which is the wrapping of the handle and the insertion of the Menuki in the grip. Each process is precise, however these are areas, I will ask other members to throw some light on, as my understanding is limited of these subjects.
Regards,
Pistolero
Rest assured Moinbhau *will* have an AMC - what with a doctor literally at his "bed and call". 
Nor do I think his passion will go anywhere but stay on the front burner with a blade ever ready for forging and heat treatment - a true lover (of blade) that he is... 
We better get that biryani out now. 
