There's rich. And then there's ridiculously rich.

To fall into the first category, you should at least be a millionaire -- and even then, as the not-so-old adage goes, a million dollars doesn't go as far as it used to. To fall into the second category, you need $100 million or more.

Indeed, not only does such a category exist; it even has its own name. According to a recent report by The Boston Consulting Group, a prestigious consulting company based in Boston, households that fall into this category are known as "ultra-high-net-worth."

Thanks in large part to soaring stock prices -- the S&P 500 (^GSPC 0.87%) is up by nearly 140% over the past five years -- this group is watching its fortunes skyrocket.

They held $7.5 trillion, or 5.5%, of global private wealth in 2012. By 2017, this is expected to grow to $11.6 trillion, or 6.8% of the world's private wealth.

As the report's authors note:

[T]he wealthy will continue to get wealthier globally. Over the next five years, global wealth among households with $5 million to $100 million in wealth will grow by a projected [compound annual growth rate] of 8.0 percent, compared with 9.2 percent for the ultra-high-net-worth (UHNW) segment (households with more than $100 million in wealth).

So, where do these folks call home?

The answer is: everywhere -- though they tend to prefer the more comfortable confines of the Western world -- for the time being, anyhow.

As you can see in the following slideshow, the United States leads the way with 3,016 ultra-high-net-worth households, followed by the United Kingdom with 1,001, and Russia rounds out the top 10 with 328 ultra-rich households.