As I write, my Lonmin (LSE: LMI) shares are worth around 170% more than they were when I bought them, just before Christmas.

I have to be honest: my investments are not usually so profitable over such a short period. When I bought the shares, I thought they had the potential to triple in value — but I expected it to take two or three years.

Should I cash in now for a quick gain, or hold on for more? This rally could easily reverse, and I might have to wait another year or two to be able to sell at the current price. Lonmin’s turnaround could still fail, leaving me in an even worse position.

Only sell on bad news?

If I’m unsure about selling, I usually continue holding until some concrete bad news emerges. That hasn’t happened yet. Indeed, a number of factors seem to be moving in Lonmin’s favour.

The price of platinum has risen by about 5% so far this year. Currency effects continue to work in Lonmin’s favour, as far as I can tell. Lower energy costs and a weak South African Rand should help keep a lid on Lonmin’s operating costs.

Another factor in support of holding onto Lonmin is that the firm’s current restructuring plans are much more substantial than anything tried before. Lonmin plans to shut a number of mine shafts and has already made more than 5,000 workers redundant this year.

Lonmin seems to have managed this without triggering industrial action or disrupting operations. This suggests to me that the group’s management and the unions that represent its workers are trying to work together to help the company survive. This hasn’t always been the case.

A final consideration is that Lonmin still looks fairly cheap, relative to historic profits. I think the odds are in favour of Lonmin’s results continuing to improve. City analysts seem to agree, and have steadily increased their forecasts for adjusted earnings per share since November.

What about 88 Energy?

The meteoric rise of 88 Energy (LSE: 88E) has understandably attracted a lot of interest. Has this firm found a source of shale oil with costs low enough to be profitable in the current market?

We don’t yet know. But it’s worth noting that the company is approaching a turning point. Last year’s Icewine #1 well seems to have been quite successful.

The firm is now planning a 2D seismic survey to prepare for Icewine #2. Final negotiations to approve funding with the firm’s lender, Bank of America, are underway and the company hopes to begin work in March.

Assuming there are no funding problems, a successful Icewine #2 well could trigger further gains for 88 Energy shareholders. But there’s no guarantee of success, and funding could become a problem once this campaign is completed. The tax rebates available for exploration costs in Alaska are set to be drastically reduced later this year.

In my view, 88 Energy remains highly speculative and quite a risky buy. If future results don’t meet or exceed investor expectations, the shares could fall heavily. A dilutive share placing or farm-out deal also seems likely to me at some point in the next year.

In reality, both Lonmin and 88 Energy carry certain risks for equity investors.

That's why it could make sense to diversify away from the commodity sector and into pharma stocks in the current market.

The Motley Fool's top investment experts have unearthed a small-cap pharmaceutical firm they believe could be significantly undervalued.

The company concerned is targeting a £4bn global market with one of its latest products. Sales are expected to rise significantly.

If you'd like full details of this small-cap pharma play, download 1 Top Small-Cap Stock From The Motley Fool today.

It's free and without obligation.

For instant access, just click here now.

Roland Head owns shares of Lonmin. The Motley Fool UK has no position in any of the shares mentioned. We Fools don't all hold the same opinions, but we all believe that considering a diverse range of insights makes us better investors.