The market may take Wall Street analysts' upgrades seriously -- at least for a day or two -- but here at The Motley Fool, we don't. Instead, we pay much closer attention to the collective knowledge of our 170,000-plus Motley Fool CAPS members. When they upgrade a stock, I like to take a second look to see why.

Here are three stocks that our CAPS members have upgraded to a lofty four- or five-star rating (out of five) over the past six months.

Company

Rating 6 Months Ago

Rating Today

Add to My Watchlist

eMagin (AMEX: EMAN) ** **** Add
Kronos Worldwide (NYSE: KRO) ** **** Add
Amarin (Nasdaq: AMRN) ** **** Add

A display business growing brighter
OLEDs are beginning to heat up as manufacturers move from research and development to production. That means lots of opportunity to solution providers like eMagin, MicroVision (Nasdaq: MVIS), and Universal Display (Nasdaq: PANL). eMagin's products are specialized for small devices and military applications, but capabilities are growing as research continues.

eMagin's stock has hit the skids since May, but some Fools are seeing that as a buying opportunity in an emerging market. CAPS member drewsd35 says: "This company is a leader in OLED technology [and] they are a mover for this technology constantly keeping on the edge." This CAPS member's outlook suggests that we may be ready for a turnaround.

Making whites whiter
Titanium dioxide may sound like a really boring business, but it's incredibly important in manufacturing. The pigment helps make colors brighter and more appealing in paint, plastic, and even the clothes we wear. A robust pricing environment means chemical makers such as Kronos and Huntsman (NYSE: HUN) have been coming in well ahead of estimates over the past year as demand outpaces supply.

CAPS member gopyerk thought the latest earnings report sent out buy signals: "I like the report from this company and the continued prospects for growth. The good news is after the split and recent downward movement this is a ripe investment opportunity."

A billion-dollar opportunity
Amarin has been on a wild ride over the past six months, with the stock popping after AMR101 showed that it significantly lowered triglyceride levels without raising bad cholesterol. But shares have fallen since management said it wasn't in a hurry to sell the company, and CAPS members think that's a buying opportunity. Eventually, the hope is that the company's drug will eventually take share from GlaxoSmithKline's (NYSE: GSK) Lovaza, which had nearly $1 billion in sales last year, but a major drug-company buyout will probably happen before Amarin launches it.

CAPS All-Star zzlangerhans thinks there's value no matter what happens: "after strongly positive results from two phase III trials, FDA approval seems highly likely. Partnership, buyout, or not I believe Amarin will rise back towards 20 once the NDA process is underway."

Foolish bottom line
A stock upgraded to four or five stars has earned a little more due diligence, if not a spot on My Watchlist. A one- or two-star rating is worth a second look and may signal that it's time to sell. Either way, the collective wisdom of the CAPS community can help steer Fools toward winning investments.