An investor's dream is to buy stock in a company that can stand the test of time and potentially pass that stock down to one's children or grandchildren. However, heirloom stocks can't be found by throwing a dart at the finance section of your local newspaper. To find heirloom stocks, you need to do some serious weeding and critiquing. 

With that in mind, we asked three of our Foolish investors to name an heirloom stock that they felt could be held forever. Rising to the top of the pack were automaker Ford Motor (NYSE:F), luxury jeweler Tiffany (NYSE:TIF), and active-apparel retailer Under Armour (C Shares) (NYSE:UA)

An old stock certificate.

Image source: Getty Images.

A company that can transcend multiple generations of investors 

Sean Williams (Ford Motor): When thinking about stocks that could, in theory, be passed down from generation to generation, I'm inclined to think of automaker Ford as a true heirloom stock. It's a company that teens who are about to get a license, and grandparents of those teens, can relate to, potentially on an emotional level.

According to Brand Keys' annual Customer Loyalty Engagement Index, a measure of customer loyalty to a brand and the engagement of that brand with consumers, Ford tied for the No. 1 spot with Hyundai in 2017.  Being at the top implies that Ford is pretty successful at keeping consumers hooked on the Ford brand, which comes in especially handy if the company is aiming to move millennials in starter sedans to higher-margin trucks, SUVs, and luxury vehicles within the next couples of years to a decade. This focus on consumer loyalty has been critical to Ford's long-term success.

The Blue Oval also has an exceptionally long-tail growth opportunity in China, where a burgeoning middle class is beginning to look for luxuries, including automobiles. Despite being the largest auto market on the planet, China is nowhere near a worrisome auto saturation level, leaving Ford plenty of opportunity to grow market share in a country that has pretty consistently grown GDP at a high-single-digit to low-double-digit percentage over the past three decades. As my Foolish colleague John Rosevear recently pointed out, sales of Lincoln have been especially strong in China, with year-to-date volume up 97%. Although the brand makes up only a small portion of total annual sales, Lincoln is a high-margin brand for the company. 

A red 2017 Ford F-150 King Ranch.

2017 Ford F-150 King Ranch. Image source: Ford Motor Company.

Domestically, I don't think investors can overlook the dominance of the F-Series pickup. As the company announced in January, the F-Series has been the best-selling truck in America for 40 straight years. Even more impressive, we're probably looking at an extension of this streak in 2017, with F-Series pickup sales up nearly 9% through June of this year. Four-decade streaks of dominance aren't an accident. They're a sign that Ford is offering consumers exactly what they want and innovating to meet their needs. That's a sign of a company that'll stand the test of time, which is what makes Ford such an intriguing heirloom stock to consider buying.

Because trinkets (and cheap stocks) aren't the ones that become heirlooms

Rich Smith (Tiffany): Diamonds, as the saying goes, are forever. So if you ask me to name an heirloom stock -- one suitable for handing down generation to generation, the first name that pops to mind just has to be Tiffany.

As a stock, Tiffany may not look like an obvious bargain. Its 2.1% dividend yield is no more than average  among S&P 500 stocks. Its 26-times-earnings valuation looks downright expensive. And Tiffany's growth rate? Analysts see Tiffany growing earnings only 9%  annually over the next five years -- which is slower than the average projection for stocks on the S&P.

All of which is beside the point.

Examining a diamond in a pair of tweezers.

Image source: Getty Images.

Listen, folks. I've bought my fair share of jewelry at online joints such as Blue Nile and Ice.com, and at bricks-and-mortar jewelers such as Zale as well. When it came time to buy an engagement ring, I hoofed it over to Laney's, my college town's incumbent local jeweler -- nearly 40 years in business, and five-star-rated on Google. Back then, of course, it was the only jeweler I knew.

Still, nothing brought a wider smile to my wife's face than the day I gifted her a simple diamond and silver pendant in that little Tiffany Blue Box. That's the mystique of Tiffany, which, perhaps immodestly, but accurately, calls its brand "an international symbol of style and sophistication." It's what makes Tiffany jewelry -- and Tiffany stock -- unique and suitable for heirlooming. Over the past decade, Tiffany stock has held its value well, averaging 25.2 times earnings over the long term -- not much different from what it costs today.

In short, don't let Tiffany's seemingly high stock price today scare you away -- because Tiffany stock is always going to command a premium valuation. That's why it's a stock you really can buy and hold forever.

Don't underestimate Under Armour

Steve Symington (Under Armour C Shares): Those who follow my musings here at The Motley Fool know I'm a longtime Under Armour shareholder. Incidentally, early this year I also singled out its C shares as an ideal stock to buy for your grandkids thanks to a combination of the brand's popularity among younger generations, the company's massive long-term growth prospects, and the stock's pullback as Under Armour's core North American apparel business showed early signs of slowing growth.

Julius Jones in Under Armour apparel, carrying a football.

Image source: Under Armour.

But shares have fallen another 25% since then as of this writing, primarily as investors lamented a continuation of those difficult industry trends that yielded Under Armour's disappointing fourth-quarter 2017 results. Shares still haven't fully recovered from that plunge, even despite staging a nearly 14% rebound last month, both as the market cheered strategic executive changes that should help foster Under Armour's global growth opportunity, and as sponsored athlete and two-time NBA MVP Steph Curry delivered an admirable performance in the NBA Finals that should bolster demand for Under Armour's Curry 4 shoe launch later this year. 

Rather than focus on Under Armour's near-term challenges in North America, investors would do well to remember its other longer-term catalysts. International sales, for one, climbed 52% year over year last quarter (57% at constant currency) to represent around 20% of total revenue and should have room to grow to more than half of sales, similar to Under Armour's larger global competitors. Meanwhile, Under Armour is still in the early stages of its recently launched foray into the multibillion-dollar sportswear category with its new Under Armour Sportswear brand.

Finally, we've only just started to see the impact of newer retail partnerships with the likes of DSW and Kohl's, and higher-margin direct-to-consumer revenue climbed a solid 13% last quarter, to around 27% of sales.  Both should go a long way toward recouping revenue lost to multiple sporting-goods retailer bankruptcies last year.

In the end, for investors willing to bet Under Armour will survive and thrive for generations to come, I think now is a great chance to open or add to a position.

Rich Smith has no position in any stocks mentioned. Sean Williams has no position in any stocks mentioned. Steve Symington owns shares of Under Armour (C Shares). The Motley Fool owns shares of and recommends Ford and Under Armour (C Shares). The Motley Fool recommends DSW. The Motley Fool has a disclosure policy.