Buying a commodity ETF might not sound exciting, but it could be a smart move for your portfolio. While investors try to diversify, they often split their nest eggs between stocks and bonds, and overlook commodities. Luckily, a commodity ETF is an easy way to fix that.

That’s not to say you should dump everything into, say, a big gold investment. But it does mean you might be better off if you use a little piece of the pie to invest in gold. Or maybe you should consider investing in silver. Really, a host of commodities have plenty of portfolio appeal.

For one, commodities have demonstrated a low correlation to other assets historically (although not always). Plus, a particular commodity ETF may make a sensible play as part of a broader thesis.

There’s no universal amount you should dump into a commodity ETF, as your risk appetite and take on the current climate for each commodity will determine that. But if you’re wondering which basic commodity ETF to consider, here’s where you should start looking.

Namely, five funds: a gold ETF, a silver ETF, a copper ETF, a platinum ETF and a catch-all commodity ETF.

Gold ETF – GLD

If you want to invest in gold, the SPDR Gold Shares (GLD) is the obvious choice for one simple reason: The gold ETF is the next-closest thing investors have to holding physical gold.

Sure, the fact that you’re not holding physical gold with this gold investment has its upsides and downsides. On one hand, a gold ETF means you don’t have to worry about the physical storage of the gold, which means no safe or sleepless nights worrying about someone nabbing your hoard.

Of course, should the world go to hell in a handbasket, each unit this commodity ETF might be based on the price of a tenth of an ounce of gold … and that bullion supposedly is sitting in vaults somewhere. However, only a few “authorized participants” are actually able to ever see a bar of it.

But that only matters if you’re picking a gold investment because you’re worried about an apocalyptic scenario. If you’re merely investing, the GLD gold ETF will do you just fine.

Sure, gold doesn’t have a ton of practical applications, but there are real drivers such as jewelry demand and central banks buying for their own stores. And for just 0.4% in expenses, or $40 for every $10,000 invested, you can invest in gold via this uber-liquid gold ETF.

Silver ETF – SLV

So if you’ve got a commodity ETF betting on gold, why would you bother with a silver ETF?

Well, much like with GLD, the iShares Silver Trust (SLV) is just a fund and doesn’t actually allow you to touch and feel the real thing. So you’re probably not investing in silver or this silver ETF because you believe it will be the world’s pocket change to gold’s primary currency of the new world order.

Instead, it’s because silver, while a shiny precious metal that does show up in jewelry, also as a number of practical applications that help prop up demand.

Sure, your mind might wander to silverware or other kitchen implements, but silver is so much more 21st century than that. Silver can be used in electronic switches, in paste or ink form, as well as LEDs and DVDs. It can be used to produce chemicals such as formaldehyde. And silver paste is even used in the manufacturing of solar panels.

Each unit of the SLV silver ETF actually represents a full ounce of silver, and again has enormous volume of hundreds of millions of units daily, making this commodity ETF a liquid, trustworthy tracker of the metal.

The SLV silver ETF charges just 0.5% in expenses.

Copper ETF – JJC

Copper is something of a stickier wicket when it comes to choosing the best commodity ETF. Unlike a gold ETF or silver ETF, which have physical backings in the metal, the most popular copper ETF options are actually exchange-traded notes.

In short, ETNs actually are debt products that are merely engineered to track a certain index — that means you’re also assuming the credit risk of whatever bank or financial institution backed the note.

Still, short of another major financial crisis, investors should be fine with the iPath Dow Jones-UBS Total Return ETN (JJC), with a couple caveats. Namely, this copper ETF isn’t for long-term holders. JJC tracks front-month copper futures, which is designed to help the commodity ETF better follow spot copper prices. But it’s not a perfect one-for-one — the futures curve also comes into play. A long way of saying, this copper ETF is a complex and far-from-ideal way to track copper.

So why invest in JJC at all? Well, for one, it’s one of the only reasonably liquid funds that tries to track the commodity at all, rather than, say, copper mining stocks. And generally speaking, a bullish play in a copper ETF often is thought of as a good way to bet on a global economic rebound because of the metal’s use in basic infrastructure items such as pipes and cables.

The commodity ETF JJC charges 0.75% in expenses.

Platinum ETF – PPLT

We’re back to the easy stuff with a platinum ETF: the ETFS Physical Platinum Shares (PPLT).

Like copper, a platinum ETF is appealing because platinum has a score of practical uses. It’s widely known for its use in catalytic converters — those frequently stolen devices under your car that help control emissions. However, platinum also can be found in dental crowns and bridges, electrical conductors and, of course, jewelry.

Of course, platinum is an extremely rare commodity, so there aren’t a ton of funds amassing bullion hoards that can back a platinum ETF. One of the few is the ETFS product, which — just like GLD and SLV — has a stack of bars behind your investment.

Unlike GLD and SLV, this platinum ETF trades just 30,000 units per day … but PPLT does have assets of about $800 million, so at the very least, it the commodity ETF shouldn’t just vanish in the middle of the night.

The PPLT platinum ETF charges 0.6% in expenses.

Broad-Based Commodity ETF – DBC

It’s not easy to choose a commodity ETF, though. You have no idea which way inflation will send gold. Is China going to put copper to use in more houses this year? If Justin Bieber goes platinum, will that send PPLT soaring?

If you’re asking yourself these questions, and have absolutely no answers, your best move is the simplest of all — a single commodity ETF that holds a basket of goods, just to give you something that isn’t stocks or bonds.

The PowerShares DB Commodity Index Tracking Fund (DBC) is a commodity ETF that does just that, charging 0.85% for exposure to 14 different commodities, including several types of oils, metals and even agricultural products such as corn, wheat and sugar.

DBC has its quirks, sure. Like JJC, this broad commodity ETF deals in futures contracts. And because of how the commodity ETF is structured — it’s technically a partnership — investors will have to fill out a Form K-1 each year.

Nonetheless, there’s few one-stop shops for commodity exposure as well-traveled as DBC, which has been around since 2006 and has racked up more than $6 billion in assets under management.

As of this writing, Kyle Woodley did not hold a position in any of the aforementioned securities.