Arabica coffee futures on ICE rose for the second straight day and flirted with a 21-month high on Thursday, on heavy fund buying as traders kept a close watch on the market's record high open interest.
Robusta coffee prices also firmed as rains slowed the pace of harvesting in top producer Vietnam, while London cocoa and sugar prices fell along with larger commodity markets.
The 19-commodity Thomson Reuters CoreCommodity Index dropped to a five-week low.
December arabica coffee settled up 2.75 cent, or 1.7 percent, at $1.6565 per lb. Total open interest rose for the 19th straight session on Wednesday, reaching a record 218,567 contracts, exchange data showed.
"The funds are piling in. They're looking for another big move," said Nick Gentile, managing partner of commodity trading advisor NickJen Capital.
As of October 25, speculators already held the biggest net long position in arabica futures and options in 8-1/2 years.
Gentile added that, though top coffee grower Brazil is getting some much-needed rain in some areas, other regions still need more rain, raising potential crop concerns.
January robusta coffee settled up $2, or 0.1 percent, at $2,166 per tonne, hovering below last week's two-year high of $2,191.
Top robusta grower Vietnam's 2016/2017 harvest has yet to pick up pace.
Dealers noted the November contract's premium to January soared to a contract high of $57, in stark comparison to a $23 discount just one week prior.
"There is still quite a large open position (on November) and not much volume," one dealer said, adding the premium indicated that supplies of deliverable coffee appeared tight.
Cocoa prices were mixed, with a favourable outlook for main crops in West Africa keeping the market on the defensive. The New York market's failure to rally painted a particularly bearish picture as it ignored the strong British sterling
against the US dollar. This is typically a source of price support for the US market.
March New York cocoa settled up $1, or 0.04 percent, at $2,633 per tonne. March London futures settled down 23 pounds, or 1.1 percent, at 2,146 pounds per tonne, pressured by the firm pound, dealers said.
Raw sugar prices eased after Wednesday's rally above the 100-day moving average and a six-week low.
March raw sugar settled down 0.22 cent, or 1 percent, at 21.48 cents per lb.
December white sugar settled down $5.80, or 1 percent, at $568.20 per tonne.