The country's Supreme Court ruled that the items worth $150,000 are now the property of the state.
The items worth $150,000 are now the property of the state, the court ruled, paving the way for the possible sale of a much larger collection of Marcos jewellery that could net the government millions.
"Petitioners failed to satisfactorily show that the properties were lawfully acquired," said the January 18 court ruling, which the court made public only this week.
The law provides that property acquired by a government official at a cost "manifestly out of proportion to his salary" or other lawful income was sufficient "presumption that they were unlawfully acquired", it added.
The jewellery in the case was recovered from the Malacanang presidential palace after the Marcos family fled to US exile in 1986, when a bloodless "People Power" revolution ended its 20-year rule.
Successor governments have cited it as proof that the family systematically looted state coffers while millions of their countrymen endured poverty.
Authorities estimated Marcos and his allies stole about $10 billion when he was in power, with less than half so far recovered through litigation and through negotiated settlements with Marcos cronies.
An anti-graft court forfeited the jewellery in favour of the state in 2009, but Imelda Marcos raised the case in the Supreme Court in 2014.
In all, the government said it had recovered about $21 million worth of Marcos jewellery, including items seized by US customs during the family's flight to exile. These were later turned over to Manila.
The entire collection, now stored at the Central Bank, includes diamond-studded tiaras, a golden belt with a diamond buckle, necklaces, brooches, earrings, belts and other gems including a pink diamond.
Previous governments pledged to auction them off.
However President Rodrigo Duterte, who took power last year, is an ally of the Marcos family and authorities would not say on Tuesday if the sale would go ahead.
Imelda Marcos, now 87, led her family back to Manila in 1991, two years after her husband died in Honolulu. She is now serving her third term in the House of Representatives.
Their only son, former senator Ferdinand Marcos Junior, narrowly lost the vice presidential election last year but filed a court challenge claiming he was cheated out of victory.
If Marcos wins, he would be vice president under family friend Duterte.
Marcos Jnr's political fortunes are based partly on persuading young Filipinos that his parents did nothing to apologise for.