Loose Diamonds: The Round Brilliant And Other Cuts

Why purchase loose diamonds? They're not necessarily as practical as earrings and necklaces. You would not be able to have them on you or display them anywhere you go. But diamonds have a beauty on their own that can't be revealed by diamonds set in jewelry. They seem even more special when they are bought for their own sake.

Diamonds are available in a variety of designs, known in the trade as cuts. The most famous of these is the round brilliant cut. Simply put, the round brilliant is the most popular because it provides the most brilliance. It has been cut in such a way that it reflects the most light. What most people don't know is that the shape of the round brilliant is the most uneconomical. As much as half of the original diamond is left out when it is turned into a round brilliant. For this reason, diamonds are sold in several other shapes as well, commonly known as fancy cuts.

Now some of the fancy cuts are already based on familiar designs, and will appeal to people even if they don't know much about diamonds. The heart and oval cuts are self-explanatory. The pear cut is often seen as an upside down teardrop.

On the other hand, how do you explain to people the differences between the Asscher and emerald cut, or the princess and radiant cut, when their shapes are the same? This is where we get a bit technical, but fortunately you don't have to get that esoteric.

Emerald and Asscher cuts are classified as step cuts. Compared to the round brilliant, they are rectangular in shape, with each side bordered with small steps. Step cuts emphasize lustre and clarity over brilliance. The Asscher cut has been popular for over 100 years, and its proportions are less even.

The princess and radiant cuts comprise a third category, known as mixed cuts. They evoke the brilliance of brilliant cuts, but are more practical to produce. The princess cut is the most popular next to the round brilliant, whereas the radiant cut has over 70 cuts.

When choosing loose diamonds, you need not be intimidated by technical knowledge. You can buy based on what cut you like. The jeweler, in turn, will narrow down your choices in terms of price and quality, and help find the best deal for you.

Diamonds are produced in a variety of designs, known in the trade as cuts. The way the round brilliant cut has been cut makes it reflects the most light. Step cuts accentuate lustre and clarity over brilliance. Mixed cuts evoke the brilliance of brilliant cuts, but are more practical to produce. When selecting loose diamonds, you need not be intimidated by technical knowledge. You can buy based on what cut you like.

An exciting range of Carabiner keychains for varied needs & budgets!

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Most popular Office Pens.

We use many types of pens in our daily life, to be included in notes to write in journals or simply documents every day. There are many brands of pens to choose from, and this article will discuss some of the best pens for office available in the market today.

Waterman Ballpoint Pen
One of the most reliable pens on the market for office, Waterman ball point pen is considered one of the best and most used in thousands of offices around the world. Built with precision technology, this pen office has an ideal balance of weight and grip very well. The ink color and clarity is good in writing this unit is always a breeze. Waterman Ball Point Pen has a refined style and feel, and is a good choice, as it is also very durable.

Pilot Dr. Grip LTD
This gel ink pen is not cheap, about $ 10 for one, but his words are wonderful, and this is the high-end pen for any office, usually used by managers and members of top management level. The LTD, although a gel pen, (which is known to loss) is completely reliable and almost always turns out to be smeared. The grip is almost perfect as silk scrolls and ink on paper. The color
ink is very dark, but still has great attributes.

BIC Intensity
This is another popular type of pen for office using a gel-based ink. This writing instrument glides smoothly, although I had the ability smudging when used on cards with glossy surfaces. In general, this pen is a reliable and inexpensive with a lifetime of impressive.

Waterford Killbarry Guilloche Rollerball Pen
This is not tehnically the run-of-the-mill office pen, but must be included for various reasons: one is solid brass and accented with faceted platinum. It 'nice to have this work of art as an anniversary gift ten years of work by colleagues or the boss. If used, the relay Killbarry Waterford exquisite texture and a feeling of luxury. The ink is dark enough, but very clear and precise on paper. He does look a little like 'a vintage fountain pen, without a pillow or grip. This is a pen used to sign the documents and not to write every day.

Uniball Jetstream Premier
This is another pen office of choice for many companies. This rollerball pen writes so smooth and has a reliable stream of ink because of a good cartridge. The Uniball Jetstream Permier action has flexible and quiet clicks, not annoying like many similar programs have disappeared. It works well for the document-writing and has a good shelf-life. The design is quite clever, but the grip is something that needs to get used to. This pen is definitely for those who make a lot of writing, such as reporting and documentation.

Pentel TKO
This is quite a reliable pen office and has been used for a while 'in many places. The shape is tapered with a tree in a clear ink levels can be observed. Comfort grip is good and easy to control. The color ink is smooth and this is cheap to boot .

SMPS

A switched-mode power supply (also switching-mode power supply, SMPS, or simply switcher) is an electronic power supply unit (PSU) that incorporates a switching regulator in order to provide the required dc output voltage.
Although the term "power supply" has been in use since radios were first powered from the line/mains, that does not mean that it is a source of power, in the sense that a battery provides power. It is simply a device that (usually) accepts commercial AC power and provides one or more DC outputs. It would be more correctly referred to as a power converter, but long usage has established the term.

Whilst a linear regulator maintains the desired output voltage by dissipating excess power in a pass power transistor, the switched-mode power supply switches a power transistor between saturation (full on) and cutoff (completely off) with a variable duty cycle whose average is the desired output voltage. It switches at a much higher frequency (tens to hundreds of kHz) than that of the AC line (mains). This means that the transformer that it feeds can be much smaller than one connected directly to the line/mains. Switching creates a rectangular waveform that typically goes to the primary of the transformer.

Usually several secondaries feed rectifiers, series inductors, and filter capacitors to provide various DC outputs with low ripple.

THe main advantage of this method is greater efficiency because the switching transistor dissipates little power when it is outside of its active region (i.e., when the transistor acts like a switch and either has a negligible voltage drop across it or a negligible current through it). Other advantages include smaller size and lighter weight (from the elimination of low frequency transformers which have a high weight) and lower heat generation due to higher efficiency. Disadvantages include greater complexity, the generation of high-amplitude, high-frequency energy that the low-pass filter must block to avoid electromagnetic interference (EMI), and a ripple voltage at the switching frequency and the harmonic frequencies thereof.

Very low cost SMPS may couple electrical switching noise back onto the mains power line, causing interference with A/V equipment connected to the same phase. Non power-factor-corrected SMPSs also cause harmonic distortion.

If the SMPS has an AC input, then the first stage is to convert the input to DC. This is called rectification. The rectifier circuit can be configured as a voltage doubler by the addition of a switch operated either manually or automatically. This is a feature of larger supplies to permit operation from nominally 120 volt or 240 volt supplies. The rectifier produces an unregulated DC voltage which is then sent to a large filter capacitor. The current drawn from the mains supply by this rectifier circuit occurs in short pulses around the AC voltage peaks. These pulses have significant high frequency energy which reduces the power factor. Special control techniques can be employed by the following SMPS to force the average input current to follow the sinusoidal shape of the AC input voltage thus the designer should try correcting the power factor. An SMPS with a DC input does not require this stage. An SMPS designed for AC input can often be run from a DC supply (for 230V AC this would be 330V DC), as the DC passes through the rectifier stage unchanged. It's however advisable to consult the manual before trying this, though most supplies are quite capable of such operation even though nothing is mentioned in the documentation. However, this type of use may be harmful to the rectifier stage as it will only utilize half of diodes in the rectifier for the full load. This may result in overheating of these components, and cause them to fail prematurely. [3]

If an input range switch is used, the rectifier stage is usually configured to operate as a voltage doubler when operating on the low voltage (~120 VAC) range and as a straight rectifier when operating on the high voltage (~240 VAC) range. If an input range switch is not used, then a full-wave rectifier is usually used and the downstream inverter stage is simply designed to be flexible enough to accept the wide range of dc voltages that will be produced by the rectifier stage. In higher-power SMPSs, some form of automatic range switching may be used.

The inverter stage converts DC, whether directly from the input or from the rectifier stage described above, to AC by running it through a power oscillator, whose output transformer is very small with few windings at a frequency of tens or hundreds of kilohertz (kHz). The frequency is usually chosen to be above 20 kHz, to make it inaudible to humans. The output voltage is optically coupled to the input and thus very tightly controlled. The switching is implemented as a multistage (to achieve high gain) MOSFET amplifier. MOSFETs are a type of transistor with a low on-resistance and a high current-handling capacity. Since only the last stage has a large duty cycle, previous stages can be implemented by bipolar transistors leading to roughly the same efficiency. The second last stage needs to be of a complementary design, where one transistor charges the last MOSFET and another one discharges the MOSFET. A design using a resistor would run idle most of the time and reduce efficiency. All earlier stages do not weight into efficiency because power decreases by a factor of 10 for every stage (going backwards) and thus the earlier stages are responsible for at most 1% of the efficiency. This section refers to the block marked Chopper in the block diagram.