Mae amgueddfa`r ddinas yn cynnal arddangosfa dros dro o emwaith brenhinol fel rhan o ŵyl gelf a chrefft

        The city museum is holding a temporary exhibition of royal jewellery as part of an arts and crafts festival

Mae`r tlysau ar fenthyg o amgueddfa fawr yn Llundain

         The jewels are on loan from a large museum in London

Aeth heddwas lleol i dafarn gyda rhai ffrindiau ar ôl gwaith

         A local policeman went to a pub with some friends after work

Fe glywodd sgwrs lle roedd gang yn gwneud cynlluniau i dorri i mewn i`r amgueddfa a dwyn y casgliad gemwaith

         He heard a conversation where a gang was making plans to break into the museum and steal the jewellery collection

Adroddodd y sgwrs i`w gydweithwyr yng ngorsaf yr heddlu

         He reported the conversation to his colleagues at the police station

Gwnaethon nhw holi cyfarwyddwr yr amgueddfa am y system ddiogelwch

         They questioned the director of the museum about the security system

Dywedodd fod staff ar ddyletswydd ym mhob oriel pan oedd yr amgueddfa ar agor

         He said that staff were on duty in every gallery when the museum was open

Yn y nos, gosodwyd larymau ar bob drws a ffenestr ac roedd teledu cylch cyfyng yn gweithredu

         At night, alarms were fitted to all doors and windows and closed circuit television was operating

Roedd yn sicr nad oedd unrhyw risg o ladrad

         He was sure that there was no risk of a robbery

Serch hynny, roedd yr heddlu`n cymryd y bygythiad o ddifrif ac yn trefnu i swyddogion wylio`r adeilad

         Nevertheless, police took the threat seriously and arranged for officers to watch the building

Yn ystod y nos, gwelon nhw ffigwr tywyll yn symud yn y cysgodion o gwmpas i gefn yr adeilad

         During the night, they saw a dark figure moving in the shadows around to the back of the building

Dringodd ysgol lle`r oedd adeiladwyr yn gwneud gwaith ar y to

         He climbed a ladder where builders were doing work on the roof

Aeth yr heddlu i mewn i`r amgueddfa a symud yn ddistaw trwy`r adeilad tywyll i`r oriel

         The police entered the museum and moved silently through the dark building to the gallery

Yma fe ddaethon nhw o hyd i leidr yn dod i lawr o ffenestr to ar raff

         Here they found a robber coming down from a roof window on a rope

Fe wnaethant aros iddo fynd at yr arddangosfa gemwaith, yna neidio arno

         They waited for him to approach the jewellery display, then jumped on him

Ffoniodd yr heddlu gyfarwyddwr yr amgueddfa i ddweud wrtho am yr ymgais i ladrata

         The police phoned the museum director to tell him about the attempted robbery

Roedd wedi synnu a dywedodd `Nid yw hynny`n bosibl - mae ein system ddiogelwch mor berffaith`

         He was astonished and said `That is not possible - our security system is so perfect`