Today I am looking at the investment case of two rising FTSE giants.

Gold play set to sink again?

Precious metals digger Randgold Resources (LSE: RRS) enjoyed a rare chug higher last week in line with a resurgent gold price, the business enjoying a 6% share price bump between last Monday and Friday.

Randgold Resources has recovered steadily over the past couple of months as investor jitters have prompted swathes of safe-haven buying into gold. But metal prices remain perched precariously above December’s lows around $1,045 per ounce, levels not visited since the beginning of 2010. And I do not believe bullion has enough fuel to push significantly higher any time soon.

The most significant bugbear for gold prices in 2015 was the steady appreciation of the US dollar as markets anticipated Federal Reserve monetary tightening. On top of this, bar and jewellery demand from the critical physical markets of China and India remained subdued.

Looking ahead, however, the prospect of further central bank purchases may provide some support. Data from the People’s Bank of China showed a sixth straight month of material additions in December, for example, taking total holdings to 1,762 tonnes. And enduring fears concerning macroeconomic cooling could lend further strength to the store-of-value commodity.

Still, I believe these factors are likely to be overshadowed yet again by additional interest rate hikes in 2016 and beyond by Fed chief Janet Yellen. Furthermore, an environment of low global inflation is likely to weigh on gold’s investment appeal this year and possibly beyond, too.

Sure, Randgold Resources may be hiking output to mitigate falling gold prices — total production registered at a quarterly record of 305,288 ounces between July and September. But this could not prevent group revenues falling by almost a tenth during the period, to £340.7m.

The City expects Randgold Resources to recover from an anticipated 24% earnings decline for 2015 with a 21% bump this year. I am not so positive over the possibility of such a bounceback given the current low-price environment, and believe a P/E rating of 27.2 times is too high given the mining giant’s high risk profile.

Masks maker should deliver mighty returns

I am far more bullish over the long-term earnings prospects over at Avon Rubber (LSE: AVON), however. And while the stock may be some way off the record highs of early November, a 2% share price improvement during the past week suggests the tide may be turning again.

On the face of it Avon Rubber may not appear the most engaging stock pick out there. Earnings are expected to slip 2% in the 12 months to September 2016 as mask orders from the US military settle from last year’s elevated levels, putting paid to the firm’s recent record of double-digit earnings growth. And a consequent P/E rating of 19.7 times rises above the watermark of 15 times generally considered brilliant value.

Regardless, I believe Avon Rubber remains a solid long-term purchase as rising geopolitical instability drives demand for the company’s industry-leading defence products. On top of this, I fully expect massive investment at the firm’s Dairy division to continue to blast demand for its milking products steadily higher, providing welcome diversification from the oft-lumpy defence sector.

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Royston Wild has no position in any shares mentioned. 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.